Language：English   Publishing type：Research paper (scientific journal)   Publisher：Informa {UK} Limited  

Numerous tsunami numerical models have been proposed, but their prediction accuracies have not been directly compared. For quantifying the modeling uncertainties, the authors statistically analyzed the prediction results submitted by participants in the tsunami blind contest held at the 17th World Conference on Earthquake Engineering. The reproducibility of offshore water level generated due to the tsunami with soliton fission significantly decreased when the nonlinear shallow water equation models (NSWE) was used compared to three-dimensional (3D) models. The inundation depth was reproduced well in 3D models. However, the reproducibility of wave forces acting on the structure and velocities over land was lower in 3D models than that in NSWE models. For cases where the impulsive tsunami wave pressure generated could not be calculated based on the hydrostatic assumption, the prediction accuracy of the NSWE models was higher than that of the 3D models. The prediction accuracies of both models were not improved at small grid-cell sizes. The NSWE model cannot simulate the short-wave component and vertical pressure distribution. Therefore, further developments in 3D models and smoothed particle hydrodynamics methods (SPH) are needed. The presented results contribute to the future development of tsunami numerical simulation tools.

DOI： 10.1080/21664250.2022.2072611

Web of Science

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Civil Engineers  

DOI： 10.2208/kaigan.78.2_i_145

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

The behavior of drifting debris at the time of a tsunami is subject to large uncertainties, and therefore it is common to use a random-motion model in numerical simulations for probabilistic evaluation. However, currently we do not have enough knowledge on the degree of variation in drifting behavior due to differences in the shape and specific weight of drifting objects, and thus we need to improve the evaluation of the variation in numerical simulations. Here we demonstrate that the effects of changing the shape and specific weight of drifting debris on drifting behavior by conducting hydraulic experiments. Based on the experiments, the variation coefficient that should be given to the drifting behavior in the random-motion model was estimated as a constant multiple of the previous value. As a result, we found that a 10 times of the previous variation coefficient can best qualitatively reproduce the uncertainty in the drifting behavior. In the future, considering a variation coefficient that takes the draft into account to improve the accuracy of drift simulations just before drifting ashore.

DOI： 10.2208/kaigan.78.2_i_421

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

To improve the accuracy of storm surge forecasting, it is desirable to improve the typhoon forecasting accuracy. The typhoon forecasting model WRF has a high degree of freedom in setting its calculation conditions. In this study, we conducted sensitivity analyses of the WRF’s calculation domain settings, initial and boundary conditions, and physics options, which have a large impact on typhoon forecasting due to the differences in their settings among model users. Here we show that (1) horizontal resolution has a greater impact on typhoon forecasting than location of calculation domain, (2) the choice of analysis data used for initial conditions of WRF has a greater impact on typhoon forecasting than lateral boundary conditions, and (3) the relationship between forecast start time and variability of storm surge forecasting due to differences in the setting of physics options of WRF. These results are useful for evaluating the uncertainty in typhoon and storm surge forecasts caused by differences in the WRF’s calculation conditions. In the future, introducing more sophisticated data assimilation (e.g., 4DVAR, EnKF) in typhoon forecasting seems necessary to improve the typhoon and storm surge forecasting accuracy.

DOI： 10.2208/kaigan.78.2_i_199

CiNii Research

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Informa {UK} Limited  

On September 28 2018, an Mw 7.5 strike-slip earthquake occurred to the north of Palu Bay on the Sulawesi Island, Indonesia. This triggered a destructive tsunami within the bay, which reached Palu city. Simulation have been conducted to investigate the landslide source. However, the tsunami should be investigated considering a physical model in the area where detailed bathymetric survey had not been conducted. In this study, we investigated the impact of coastal landslides on the southern part of the bay using a two-layer model. Owing to the increasing collapse volume, the southern west coastal landslide could approximately explain the observations in Palu city. However, the calculated mass volume of the source largely overestimated the bathymetric survey data. Hence, we considered the possibility of submarine landslide in the southern part of the bay and the simulation results could approximately explain the maximum tsunami heights in the southern part of the bay. These results suggest that more detailed multibeam data will be required to investigate the possible submarine landslide in the southern area which could induce a destructive tsunami reaching Palu city within a few minutes after the collapse.

DOI： 10.1080/21664250.2021.1933749

Web of Science

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Fuji Technology Press Ltd.  

Assessing the risk of tsunami-driven debris has increasingly been recognized as an important design consideration. The recent ASCE/SEI7-16 standard Chapter 6 requires all the areas included within a 22.5° spreading angle from the debris source to consider the debris impact. However, it would be more reasonable to estimate the risks using numerical simulation models. Although a number of simulation models to predict tsunami debris transport have been proposed individually, comparative studies for these simulation models have rarely been conducted. Thus, in the present study, an inter-model comparison for tsunami debris simulation model was performed as a part of the virtual Tsunami Hackathon held in Japan from September 1 to 3 in 2020. The blind benchmarking experiment, which recorded the transport of three container models under a tsunami-like bore, was conducted to generate a unique dataset. Then, four different numerical models were applied to reproduce the experiments. Simulated results demonstrated considerable differences among the simulation models. Essentially, the importance of accurate modelling of a flow field, especially a tsunami front, was confirmed to be important in simulating debris motion. Parametric studies performed in each model and comparisons between different models also confirmed that a drag coefficient and inertia coefficient would influence the simulated debris trajectory and velocity. It was also shown that two-way coupled modelling to express the interaction between debris and a tsunami is important to accurately model the debris motion.

DOI： 10.20965/jdr.2021.p1030

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Elsevier {BV}  

DOI： 10.1016/j.coastaleng.2021.103970

researchmap

J-GLOBAL

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

Numerous combinations of disaster reduction facilities should be taken into consideration to evaluate the damages of inundation due to probabilistic tsunami hazard. In this study, we implemented it and investigated how the tsunami inundation probability changes by using the levee fragility model. coRaL method was used to obtain the inundation depth exceedance probability and applied to two different terrains. The results showed that the probability was between the case of overtopping and collapse and the case of overtopping but no breach, which was found to be reasonable, and they support the effectiveness of levee fragility model.

DOI： 10.2208/kaigan.77.2_i_223

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

In order to improve the accuracy of storm surge prediction in real time, it is necessary to improve the accuracy of typhoon prediction. For this purpose, it is important to properly set the calculation conditions of meteorological models, which have often been determined empirically. In this study, we developed a system using machine learning to automatically suggest combinations of physics options of the WRF to achieve the highest prediction accuracy for newly generated typhoons. As a result, we confirmed the improvement of typhoon forecasting accuracy by using this method, which selects physics options of WRF based on typhoon characteristics such as the position of typhoon occurrence, the maximum diameter of the wind field and so on. In addition, by using the typhoon prediction results as the external force for storm surge estimation, the prediction accuracy of maximum storm surge was improved on average in many locations, and in some locations the accuracy was significantly improved, indicating the effectiveness of our method, although further verification is required.

DOI： 10.2208/kaigan.77.2_i_139

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

When a tsunami strikes, not only structures but also many people are swept away, leading to an increase in the number of missing and dead people. It is important to predict the behavior of drifted debris and the extent of drift after a tsunami in order to protect facilities and save lives. However, the drift behavior is highly variable. In this study, the effect of the initial position on the drifting behavior was experimentally investigated. The results showed that the degree of variability increases with the drifting distance, and the relation between the distance and the variability perpendicular to the drifting direction in this experiment was presented. In the numerical calculation, it was confirmed that the drift direction was in good agreement with the average of the experimental values, although there was some variability.

DOI： 10.2208/kaigan.77.2_i_313

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

In this study, the effectiveness of the movable breakwaters for reducing the water level and preventing storm surge was investigated at Tokyo Bay under the worst-case scenario based on an empirical typhoon model. As a result, the water level reduction effect of the movable breakwaters at the harbor was 11.2-42.2 % for each installation and 27.4-45.7 % for multiple installations in the typhoon path where the maximum stormsurge was observed. In addition, it was found that the multiple installation of the system was effective for reducing the water level in the river, while the installation of the system only at the mouth of the river was sufficient to prevent stormsurge. In addition, a comparison the method of raising the levee, conventional strengthen-ing, and the movable breakwaters on the inundation control effect showed that the movable breakwaters was more effective than the method of raising the levee uniformly by 3.0 m in the case that install multiple breakwaters in the harbor and in the river.

DOI： 10.2208/kaigan.77.2_i_823

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

In this study, a method for predicting the drift of vessels during typhoons is developed, and the accuracy of predicting the drift of vessels is investigated by calculating the drift using various weather prediction models. The prediction method is based on the domain meteorological model WRF, the Japan Meteorological Agency's GSM (Japan region), and the forecast data of MSM. The results of the prediction calculations showed that, on average, the error of the predicted drifting position from the measured value was about 1 to 4 km, but in the case of a vessel at anchor, the prediction accuracy of the drifting wake and the drifting point was higher in the case with a higher prediction accuracy of the wind field. However, in order to improve the accuracy of predicting the anchorage of a vessel during a typhoon, it is necessary to take into account various uncertainty factors, such as the anchor chain, waves, and the use of the main engine, in order to improve the calculation accuracy, such as the conditions for the start of drifting.

DOI： 10.2208/kaigan.77.2_i_1015

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

We propose the coRaL method (a method of incorporating Random phase model into Logic tree approach), which is a probabilistic tsunami hazard assessment method with a high objectivity by reforming the evaluation method of earthquake asperity model and the concept of aleatory uncertainty among the probabilistic methods using logic tree approach conventionally used in Japan. The proposed method is applied to the cities located along the Pacific coast where the tsunami risk due to the Nankai Trough megathrust earthquake is assumed. We show that the proposed method can evaluate the tsunami inundation depth distribution for each return period (e.g., 150 years, 500 years, 1000 years, 2500 years), and for each percentile considering the uncertainty of tsunami hazard assessment even for the same return period.

DOI： 10.2208/kaigan.77.2_i_175

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

Since the event of the 2018 Palu tsunami in Indonesia, the countermeasures for reducing tsunami damage have been considered in Palu city where the destructive landslide tsunami event occurred. The tsunami induced by landslide in the Palu bay could reach the coastline of Palu city within a few minutes. On the other hand, there is a possibility that the tsunami induced a subduction-zone earthquake along the Makassar strait could cause the larger inundation area than that of landslide tsunami, although the tsunami could reach the coastline 20 minutes or more after the earthquake.

 In this study, we investigated an effective countermeasure for complex disaster of landslide tsunami occurring in the Palu Bay and anticipated maximum tsunami induced by a subduction-zone earthquake along the Makassar strait in Palu city based on reconstruction plan in the Sulawesi island. We selected the evacuation facilities based on tsunami hazard map of Palu city and assumed the elevated road along the coastline of Palu city to investigate the effect of tsunami damage reduction. As results of evacuation simulation, the elevated road and appropriate selection of evacuation facilities could reduce the mortality rate of the landslide tsunami. Moreover, the importance of establishment of evacuation facilities which could resist against the tsunami induced by the subduction-zone earthquake was implied by the presented examination.

DOI： 10.2208/kaigan.77.2_i_241

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

Issues related to climate change in coastal areas have been addressed in a wide variety of academic fields and societies, including meteorology, marine physics, chemistry, biology, ecology, policy science, and economics. However, the efforts and initiatives of each relevant academic field or society are rarely shared because climate change science is so interdisciplinary. Furthermore, climate change issues in coastal areas can be studied from the perspective of current status, future prediction, impacts on natural phenomena and human activities, and mitigation and adaptation measures. However, there have been no studies examining researchers’ priorities in their respective academic fields, or issues for such studies in the future. In the present study, we conducted a survey concerning “Future Challenges to Address Climate Change in Japanese Coastal Areas” involving a variety of the member of academic societies interested in climate change. The results show that the top 10 keywords for future challenges to addressing climate change problems in coastal areas were “air and sea temperature”, “decline in biodiversity”, “sea level rise”, “extreme weather and climate”, “greenhouse gas”, “degradation of ecosystem services”, “typhoons and low pressure”, “decrease in fishery products”, “land loss and coastal erosion”, and “fishery management”. Clearly, the respondents placed a high priority on topics involving natural phenomena and human activities, but a low priority on climate-change countermeasures. This tendency was true both for individual keywords and for all the selected keywords together. The reasons for the keyword selection result are discussed, and the current status, future challenges and prospects in Japan are summarized for the top 10 keywords.

DOI： 10.2208/kaigan.77.1_1

CiNii Research

researchmap

Other Link： https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-19K15106/

Language：Japanese   Publisher：Japan Society of Civil Engineers  

The prediction and control of wave motions during the installation of a caisson can improve the efficiency of the work. In this study, the oscillation of a caisson is investigated using a solid-gas-liquid three-phase numerical wave tank, which can analyze the movement and deformation of structures and the contact between structures due to fluid motion, and the results of numerical calculations are compared with those of hydraulic model experiments. As a result, the maximum displacement and its tendency were in good agreement with the hydraulic experiment by changing the grid size. The collision between the caisson and the mound was also investigated by changing the water draft, and it was shown that the oscillation decreased with increasing the water draft. The trend is in good agreement with that of Horisawa et al.¹⁾, indicating the importance of coupled analysis between fluid and structural analysis.

DOI： 10.2208/kaigan.77.2_i_775

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

In this study, the lift pressures acting on a horizontal slab due to traveling and overlapping waves were analyzed using a gas-liquid two-phase numerical wave models, and the pressure reduction effect by adding holes to the slab was investigated. As a result, it was confirmed from the numerical simulation that the pressure caused by the air compression was generated when waves did not reach to the horizontal plate. In addition, it was found that the pressure due to air compression was reduced to some extent by adding an aperture, and the reduction rate depended on the relative clearance and aperture ratio. For future studies, the response of the structure and the multi-directional irregular waves should be investigated to improve the versatility of the practical design.

DOI： 10.2208/kaigan.77.2_i_727

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

In this study, as an initial step for instantaneous tsunami arrival time prediction after an earthquake, we used images of the initial water level obtained from numerical tsunami simulations for the Nankai Trough to predict the tsunami arrival time using machine learning. The arrival times were pre-processed and colored every 3 minutes and every 2 minutes for training. The accuracy of the tsunami arrival time prediction was improved by increasing the number of training data, and the error of the tsunami arrival time was within 3 minutes in some places. In addition, we compared the prediction accuracy of A town and B city in Mie prefecture to confirm the difference. Although the inundation area is overestimated and the arrival time is currently overestimated or underestimated, the arrival time of the tsunami is generally predicted well by machine learning based on the initial water level information.

DOI： 10.2208/kaigan.77.2_i_307

CiNii Research

researchmap

Language：Japanese   Publisher：The Japan Society for Industrial and Applied Mathematics  

Abstract. Siltfence is a curtain-like structure to prevent the spread of suspended pollutants generated by constructions in rivers or coasts, and its shape deforms horizontally and vertically. In this paper, we propose a modeling method to simulate the siltfence deformed in the two directions by coupling with water flow dynamics. We preform numerical simulations on a siltfence installed in flume using the proposed method, and we confirm its validity by comparing between the simulation and flume experiment.

DOI： 10.11540/jsiamt.31.1_20

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

Coastal vegetation, such as coastal forests and mangroves, has been focused on its mitigation effects as green infrastructure. However, the current numerical calculation speeds do not allow for detailed modeling of vegetation with complex root structures. In this study, we aimed to establish a low-cost calculation method for mangroves by using the porosity. The validity of the method was verified by comparing with physical experiments, and the disaster mitigation effect of a raised road was examined using the cross-sectional shape of the local site. The numerical results are consistent with the experimental results, although they are slightly underestimated.

DOI： 10.2208/kaigan.77.2_i_913

CiNii Research

researchmap

J-GLOBAL

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

For the scour protection against local scouring phenomena in the foundation of monopile offshore wind farms, there are still many quantitative studies on the necessary scour protection area. In addition, it is necessary to consider the scale effect in hydraulic model experiments dealing with geomaterials. In this study, we conducted experiments at two different scales, 1/65 and 1/130, compared to the previous large-scale experiment at 1/13 scale. From the experiments, the appropriate similarity law for the geomaterials including the scour protection works was confirmed, and the effectiveness of the scour protection works was discussed. The scour depths of each experiment were compared based on the similarity of the sedimentation rates, and the results showed that the experiments were reproducible. It was also found that a scour protection radius of about 1.5 times the diameter of the monopile was sufficient to counter the effects of the flow alone.

DOI： 10.2208/kaigan.77.2_i_559

CiNii Research

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

J-GLOBAL

researchmap

Publishing type：Research paper (international conference proceedings)  

Scopus

researchmap

Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)   Publisher：京都大学防災研究所自然災害研究協議会  

令和元年台風19号では, 東日本の非常に広い範囲で長時間の豪雨をもたらし, 大規模な洪水氾濫が発生すると共に, 台風による過去最多の士砂災害件数, 竜巻などの強風被害, 記録的な高潮・高波被害が発生し, 甚大な人的・物的被害が生じた。その約2週間後には, 日本南岸の低気圧と台風21号による大雨が発生し, 千菓県や福島県などにて洪水氾濫が発生した。本研究では, 科研費・特別研究促進費による突発災害調査研究により, 台風19号, 21号による広域災害について, 全国から多分野の研究者が集結した総合研究を実施した。本報はその成果の一部を取りまとめたものである。また, 今後に向けての提言も一覧できる形でまとめている。
2020年9月1日(火), 於 : Zoomによるオンライン開催

CiNii Research

researchmap

Language：Japanese   Publisher：東北大学災害科学国際研究所(津波工学研究分野)  

CiNii Books

CiNii Research

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Informa {UK} Limited  

DOI： 10.1080/21664250.2020.1744212

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：TAYLOR & FRANCIS LTD  

Typhoon Faxai caused severe damages along the western shore of Tokyo Bay, Japan in September 2019. Retaining a relatively small radius of maximum wind, Faxai passed across the center of Tokyo Bay and caused intensive wind and waves. While the sea level anomaly recorded at several tide gauge stations along Tokyo Bay were at most 1 m, and no significant surge-induced inundation was found, locally concentrated damages and wave-induced hazards were observed around Yokohama, on the middle-western shore of Tokyo Bay. The observed inundation height around Yokohama was TP (Tokyo Peil) 4.2 m on average, and the highest runup, TP 10.8 m, was observed at a small hill directly behind the seawall in Fukuura, Yokohama. The estimated wave overtopping directions at each location varied from the northeast to southeast, and no clear correlation was found between the wave overtopping directions and the extent of observed coastal hazards. Based on these findings and investigations of recorded data such as wind and waves, it was deduced that locally concentrated damages and hazards around the middle western shore of Tokyo Bay may be explained by the unique features of a relatively compact Faxai and the topographical characteristics of Tokyo Bay.

DOI： 10.1080/21664250.2020.1738620

Web of Science

Scopus

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

Previous studies have shown that siltfences reduce the effect of preventing the spread of pollutants when flow velocity was increased. However, under the present circumstances, it may be necessary to use siltfences even under the condition that flow velocity is high. On the other hand, there is also an example that installation of multiple siltfences can efficiently prevent pollutants. In this study, a hydraulic experiment was conducted for quantitative evaluation of the diffusion prevention effect of pollutants using silefences under high-speed flow.

 As a result, it was found that the pollutants were more trapped by the influence of the first siltfence and the reduction of the puffing amount of the second siltfence. The deformed shape of the second siltfence was reproduced by using the previously proposed estimation formula with appropriate experimental constants. This effect was confirmed in the experiment using plane wave tank.

DOI： 10.2208/kaigan.76.2_i_103

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/030805706

Language：Japanese   Publisher：Japan Society of Civil Engineers  

Numerical simulations are now being applied in place of the physical model experiments that have been used in the design of maritime structures. In this paper, the transition from model experiments to numerical simulations in the field of design of maritime structures is investigated. For wave deformations such as wave shoaling and wave breaking and reflected waves of long-period waves, it is now possible to shift from physical model experiments to numerical simulations. Numerical simulations can be performed on wave pressure, wave overtopping, and transmitted wave, but when applied to actual design, accuracy verification is required and calculation speed is desired to be improved. At present, it is difficult to apply numerical simulations for phenomena accompanying movement of objects such as caisson sliding and wave dissipating block movement to actual design.

DOI： 10.2208/jscejoe.76.2_i_115

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

As a countermeasure for reducing tsunami damage, it is necessary to consider evacuation support and evacuation actions based on tsunami arrival time. Many recent tsunami evacuation assistances only have showed the inundation area, information of evacuation site, and shortest route to evacuation sites. However, safety of routes to evacuation shelters based on the estimated inundation range and estimated tsunami arrival time has not been considered.

 Based on the earthquake information, we searched scenarios from the tsunami database that tsunami simulation results are accumulated. Then, we extracted a scenario based on search range, magnitude and estimated tsunami arrival time. We constructed an evacuation route search method to avoid tsunami encounter considering the tsunami arrival time on the evacuation route of the extracted scenario.

 We then examined the effectiveness of our proposed method at Katsuura City, Chiba Prefecture. As a result, when evacuation was started both before and after the arrival time of the tsunami, the mortality rate was reduced by selecting the route which doesn’t encounter tsunami. This implies the effectiveness of our proposed evacuation support method which can provide a safe evacuation route.

DOI： 10.2208/kaigan.76.2_i_1249

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/030808791

Language：Japanese   Publisher：Japan Society of Civil Engineers  

Field survey of bathymetry, sediment and bedrock of the narrow in Kesennuma Bay have been investigated. Numerical simulations of tsunami-induced sediment transport during the 2011 Tohoku tsunami were also improved by using the bedrock and sediment dataset. After the tsunami, depositions at the center of the narrows, erosions at the sides and the north area, and depositions at the south area were confirmed. By utlizing the bedrock data, the reproducibility of the field modeling was improved although the erosion of the narrows was limited to the bedrock distribution. It was found that the introduction of the bedrock is important to prevent underestimation of flow velocity and topographic changes. Furthermore, the simulations with simple consideration of erosion resistance due to the geology showed that the effect of erosion resistance was small and within the range of conventional modeling. The erosion speed in the narrows was characterized during the rising and the stationary period of the Shields parameter.

DOI： 10.2208/kaigan.76.2_i_427

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/030806502

Language：Japanese   Publisher：Japan Society of Civil Engineers  

Many hydraulic experiments have been carried out on the physical elucidation of lift force and shock wave pressure. In recent years, computational techniques have been developed and wave pres-sure is being studied using numerical calculations. However, there are few case studies by numerical calculation for phenomena such as lift force because it makes huge time to calculate complex wave pressures. In this study, we conducted hydraulic experiments on the pier, and compared with the cal-culations using the gas-liquid phase fluid simulation. Furthermore, we investigated the accuracy of reproducibility calculations for incompressible fluid and possibility of applying calculation to prac-tice. Although, it remains problem to reproduce the experimental values sufficiently by numerical calculation, it was possible to catch the momentum of the water mass. It is necessary to study the compression effect and the reduction of calculation cost.

DOI： 10.2208/kaigan.76.2_i_787

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/030807159

Language：Japanese   Publisher：Japan Society of Civil Engineers  

Regarding the local scour phenomenon at the base of a monopile type offshore wind power generator, although some existing formulas have been proposed, the effect of the countermeasure construction has been still unclear. In this study, we investigated the effect of countermeasure construction and conducted the reproduction of the local scour phenomenon using large-scale experiments and numerical calculations. We conducted the experiment under the condition that waves, current, and both waves and current are existed using 50 cm monopile with a scale of 1/13, then investigated the scuring depth in case that countermeasure construction was installed and not installed. As a result, it was confirmed that the countermeasure construction has a effect to reduce scaring around the monopile. We then conducted the calculation of flow around the monopile using three-dimensional numerical simulation. The computed results were consistent with the measured values, thus the validity of our simulation was confirmed. Although the scouring depth and its mechanism have not been elucidated, it is qualitatively inferred that the scouring was occurred due to the relationship with the local velocity and vorticity.

DOI： 10.2208/kaigan.76.2_i_535

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/030806611

Language：Japanese   Publisher：Japan Society of Civil Engineers  

It has been reported that the optimal route can be used to CO₂ during ship navigation, and it is important to predictthe wave field around the ship up to several hours ahead. In order to improve the avvuracy of local and short-term predictions such as the around field around ships, it is necessary to develop a mechanism to correct the prediction using ship observational data. Therefore, in this study, we constructed a data assimilation system that applies EnKF to a wave prediction model SWAN, in order to make wave predictions using real-time observational data obtained from ships. As a result, improving the accuracy of the ship position and usefulness of EnKF were shown by performing data assimilation using ship observational data. Moreover, in order to improve the accuracy in coastal area and the accuracy of the whole sea by increasing the number of observation points, we investigated the accuracy using NOWPHAS wave observational data. Compared with the estimation accuracy before data assimilation, the accuracy was improved about 27 % at the maximum.

DOI： 10.2208/kaigan.76.2_i_241

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/030806213

Language：Japanese   Publisher：Japan Society of Civil Engineers  

In this study, in order to contribute to the prediction of drifting ships during a typhoon, we examined the variations of size and moving distance of ships located in Tokyo Bay during the typhoon no. 15 and 19 in 2019. As a result of AIS data analysis, moving distance of ships become long if the size of ship is small. We also conducted numerical simulation for reproducing drift of ships which reached the collision during the typhoon no. 15. But time series of ship position could not be reproduced. The averaged wind speed and direnction were reproduced well in our simulation. Thus, it is likely that local wind affects to drifting of ships. In addition, in the case of changing the anchorage position, the result was that the collision was evaded considering the drift distance and wind field at that time.

DOI： 10.2208/kaigan.76.2_i_853

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/030807210

Language：Japanese   Publisher：Japan Society of Civil Engineers  

Coastal boulders formed by past tsunami or storm waves have been reported around the world. The relationship between size of tsunami or storm wave and boulder weight is nesssary to be investigated in more cases for contributing the research of coastal boulders to future disaster prevention at coastal area. At Okinoshima, Chiba prefecture, several tones of coastal boulders were transported by storm waves during the 2019 Typhoon No. 15 (Faxai). In this study, we conduected numerical simulation of storm waves during this event in order to estimate ths size of storm wave which emplaced these boulders onto the land. As a result, we estimated that the maximum size of boulder was transported from areas that water depth is less than 9.1 m. The computed maximum wave height and velocity over the shoreline was respectively 4.7 m and 14.5 m/s. Hereinafter, by accumulating the data of boulder distribution and size of tsunami or storm wave, the estimation of past tsunami or storm wave that transported coastal boulder can be conducted in many places.

DOI： 10.2208/kaigan.76.2_i_1165

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/030808435

Language：Japanese   Publisher：Japan Society of Civil Engineers  

We conducted the prediction in case of the 2019 typhoon Hagibis to examine the accuracy of the surge and waves prediction using global WRF. We obtained the most reliable sustained maximum wind speed and peak value of surge and significant wave height in case that simulation of the typhoon was started approximate 1000 km offshore from Japan coast. The predicted maximum storm surge was underestimated because the propagation speed of typhoon was underestimated and the wind direction was different from the observation. In addition, in the real-time prediction, we have to consider computation time and computation efficiency not only prediction accuracy. However, the appropriate model configuration from this point of view hasn’t been investigated, yet. To achieve the cost-effective storm surge and waves prediction with high accuracy, the relations among prediction accuracy, computation time, and computation load should be generalized. The results of this study presented the best prediction start timing to achieve the cost-effective prediction in case of the 2019 typhoon Hagibis. More prediction cases must be accumulated to generalize the model configulations.

DOI： 10.2208/kaigan.76.2_i_247

DOI： 10.2208/kaigan.77.2_i_139_references_DOI_JFPhVJsMVWBwVIqHxjd5YErZwpF

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/030806216

Language：Japanese   Publisher：土木学会海洋開発委員会  

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

We conducted a hydraulic experiment in case that tsunami debris set on the land model. The tsunami debris was drifted at the tip of a runup wave and collided with the reflection wall. Then, we examined the effect of reducing the collision speed due to the buffer effect which occurred at the tip of the runup wave that firstly collided with the reflection wall. We also conducted experiments under the several conditions to examine why the length of reflected waves become increase. We examined the effect of the water mass against the collision probability and the collision speed under the condition that the runup wave and the water mass reflected by the wall coexist. In addition, it became possible to evaluate the collision velocity from "the reduction rate of the drift speed due to the reflected water mass" and "the length of the reflected water". Furthermore, we succeeded to evaluate the collision velocity using the theoretical equation of reducing collision speed in the reflected wave, quantitatively.

DOI： 10.2208/kaigan.76.2_i_685

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/030806939

Language：Japanese   Publisher：Japan Society of Civil Engineers  

Aiming for the advancement of historical and prospective tsunami scale evaluations, and focusing on the tsunami run-up, series solutions to the tip position a(t), velocity U (=da/dt) and acceleration d²a/dt² in the tip region of inundation flow with sediment over a uniformly sloping bottom under the condition that the friction factor K is not linked to the density ρ of inundation water and analytical solutions to a(t), U, d²a/dt², the maximum run-up distance a_m and height R_m under the condition that K is linked to ρ are derived, and effects of ρ on them and run-up process are theoretically examined. It is indicated that (1) in the run-up analysis (including numerical simulation) of tsunami with sediment under the condition of a constant K, even if a_m and R_m can be predicted accurately, there is a possibility of evaluating the run-up duration time inaccurately and vice versa, and (2) linking K to ρ is necessary to solve this matter. An expression for the relationship between K and ρ is also presented. Moreover, it is verified that the derived series and analytical solutions are useful to discuss the effects of ρ on the run-up of tsunami with sediment through a comparison between the experimental and theoretical maximum run-up distances.

DOI： 10.2208/kaigan.76.2_i_391

CiNii Books

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/030297342

Language：Japanese   Publisher：Japan Society of Civil Engineers  

When tsunami contains sediments, its wave force become strong due to increase of its density. This has a great influence on building damages. The sediment diameter collected from the tsunami at the time of the 2011 Tohoku-oki earthquake remained in Kesennuma City, Miyagi Prefecture was 6.74 µm, which is classified as silt. Tsunami wave force which contains sand sediments or silt has not been investigated. In this study, we conducted laboratory experiments on tsunami containing sediment. We then showed the tendency by investigating wave force, coefficient of wave pressure, angle of water surface, and its density. As a result, when density of tsunami was increased, it is likely that tsunami wave force become high and angle of wave front become variable when tsunami collides with vertical wall. We also showed that it is likely that wave pressure of tsunami is relatively increased when tsunami contains sediments even if Froude number is same.

DOI： 10.2208/kaigan.76.2_i_385

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/030806317

Language：Japanese   Publisher：Japan Society of Civil Engineers  

In this study, in order to validate the modeling of coastal forest within surf zone based using the three dimensional simulation, the simulation results and experimental values were compared. Laboratory experiments for revealing attenuation of wave height due to coastal forest has been conducted. After the validation of our numerical simulation, drag and inertial coefficients were estimated. It was confirmed that the trend of the both coefficients characterized by Keulegan-Carpenter and Reynolds number are consistent with the results estimated by the previous study.

DOI： 10.2208/kaigan.76.2_i_955

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/030807338

Language：Japanese   Publisher：東北大学災害科学国際研究所(津波工学研究分野)  

CiNii Books

CiNii Research

researchmap

Publishing type：Research paper (scientific journal)   Publisher：Informa {UK} Limited  

Typhoon Jebi in 2018 caused severe damage along areas of Osaka Bay, Japan. After the storm, a Japan Society of Civil Engineers (JSCE) coastal survey group surveyed the coastal impacts and recorded watermarks inside Osaka Bay and along the Pacific. The maximum storm tide recorded by a tide gauge was 3.29 m at the Osaka Tide Station, which is a historical high for Osaka Bay. Coastal flooding consisted of both storm surge and wave run-up in almost all locations, with flooding exceeding 5 m and 12 m in elevation from mean sea level in the inner parts of Osaka Bay and along the Pacific coast, respectively. Coastal damage was severe in areas located outside of coastal barriers, such as ports and harbors, while residential areas were mainly well protected and spared due to coastal protection systems. In addition, some inland flooding occurred in the Kobe-Ashiya regions due to the storm surge propagating up several small rivers. This survey report summarizes the findings of the post-event survey by JSCE and analyzes the relation between maximum water level and resulting damage.

DOI： 10.1080/21664250.2019.1619253

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Informa {UK} Limited  

Hurricanes Irma and Maria caused catastrophic damages across the Caribbean Islands during the 2017 hurricane season. After the storms, a joint United States-Japanese team investigated coastal impacts in the US Virgin Islands, which are composed of the islands of St. Thomas, St. John, Water Island, and St. Croix. Coastal inundation was dominated by wave run-up in almost all locations, with many locations showing inundation exceeding 4-m elevation from mean sea level. In contrast, maximum elevations recorded at tide gauges did not exceed 1 m at any location. Coastal damage was relatively minor for such strong hurricanes because of the lack of heavy development at low elevations on the most exposed coastlines. Many moored vessels were destroyed, and coastal structures and infrastructure within the inundation region suffered significant damage. However, few large structures experienced catastrophic losses from coastal inundation. In contrast, strong winds caused extensive structural damage throughout the US Territory. Evidence was seen for past inundation of the coastline, but could not be conclusively linked to any particular events.

DOI： 10.1080/21664250.2018.1558920

Web of Science

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

In order to evaluate coastal geomorphic changes and potential impacts of tsunami-induced sediment transport in Kochi Prefecture caused by the Nankai Trough megathrust earthquake, numerical simulations of sediment transport over a wide area of Tosa Bay have been performed. The regional features of potential impact was provided. The tsunami-induced sediment transport can cause not only large-scale erosion and sedimentation around the coastal zone but also increase in tsunami hazards. Note that the influences depend significantly on uncertainties in bed materials, i.e. grain sizes and distributions of erodible/noerodible surfaces. The uncertainties in the simulations will be improved through acquisition of detailed sedimentary data. Further discussions considering the regional characteristics of tsunami-induced sediment transport will provide the resilient countermeasures to tsunami disaster.

DOI： 10.2208/kaigan.75.i_685

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/030112177

Language：Japanese   Publisher：Japan Society of Civil Engineers  

In this research, a laboratory experiment of sand leakage into the mound of wave dissipating blocks was conducted in the scale of 1/100.

 Afterwards, the result was compared with the large-scale experiments conducted in previous studies. However, sand leakage observed differed considerably between the different scale experiments; sand leakage in the large scale was not generated in the laboratory experiment. Moreover, from further research, it was revealed that the ratio of grain sizes to sand layer of the mound is a significant parameter for sand leakage to occur.

DOI： 10.2208/kaigan.75.i_547

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

In recent years, sea conditions are becoming severe due to climate change. In addition, it is required to cope with the action of multiple forces. There are cases where the conventional hydraulic model experiment facilities can not cope with these changes in the situation in recent years. Therefore, it is intended to organize the existing hydraulic model experiment facility and propose a hydraulic model experiment facility to clarify the mechanism of response to climate change and complex disasters.

DOI： 10.2208/jscejoe.75.i_349

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

As a result of the Great East Japan Earthquake, coastal structures were submerged by the tsunami. Part of these structures were scoured, resulting in a reduction of the bearing capacity of these structures. As a result, some caissons were moved and some of them were collapsed, although the actual tsunami water depth did not exceed the threshold which can slide the caisson. For designing of a robust structure, the investigation of the influence against scours behind the seawall due to tsunami is important. Although many studies has conducted the estimation of the maximum scour depth, few studies actually have investigated the relationship between overflow time and scour depth.Therefore, the purpose of this study is to design an experimental equation that can evaluate the time evolution of scour depth.

DOI： 10.2208/kaigan.75.i_715

CiNii Research

researchmap

Other Link： https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17H01293/

Language：Japanese   Publisher：Japan Society of Civil Engineers  

In this study, we simulated the drifting of vessels during the 2018 typhoon JEBI that attacked on the Kinki region on September 4, 2018 for future prediction of vessel drifting by typhoon. For the simulation, the wind field of the typhoon was created using an empirical model. The wind speed and direction in the simulation are calibrated with the observed values. Then, we examined the wind direction due to difference in deflection angle of typhoon. The wind direction was also adjusted to fit with the tracks of the vessels, then wind acts on the vessels was calculated. As a result, the calculated drifting direction and distance of the vessels were consistet with the observed ones. The calculated drifting speed was approximately reproduced well, but some discrepancies between calculated and observed values were confirmed.

DOI： 10.2208/kaigan.75.i_301

DOI： 10.2208/kaigan.76.2_i_853_references_DOI_AVHEFg1Fp3U8Bv028hU4m0isOV5

CiNii Research

researchmap

Other Link： https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17H01293/

Language：Japanese   Publisher：Japan Association for Wind Engineering  

DOI： 10.5359/jawe.44.288

DOI： 10.2208/kaigan.76.2_i_1219_references_DOI_RyZFcmryrDmh2xgrq9iz5ep9aML

CiNii Books

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/029921583

Language：Japanese   Publisher：土木学会海洋開発委員会  

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

A combination of quasi three-dimensional and three-dimensional models is required for reasonable and rapid real-time storm surge forecasting. It is also important to clarify the adaptability conditions of quasi three-dimensional and three-dimensional models. However, there are few studies which examined the adaptability conditions on minor islands because the possibility of storm surge disaster at these islands is quite low compared to the inner bay. In this study, we examined the applicability of quasi three-dimensional and three-dimensional models during the 2017 Hurricane Irma which caused storm surges around Caribbean Sea. We also examined the accuracy of computed three-dimensional velocity induced by its hurricane passage. As a result, it was clarified that three-dimensional model is necessary for modeling storm surge on minor islands. This is because the multi-layered cells contribute to the propagation of storm surge when water depth become small. The computed storm tide become high due to the wind set-up around the island area, but this storm tide caused by wind set-up effect can be estimated properly using three-dimensional model.

DOI： 10.2208/kaigan.75.i_259

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

In this research, the protective performance of the movable breakwater with gap against the long waves like storm surge was examined by physical experiment and numerical simulations. In the hydraulic experiments, the characteristics of the flow through the gap were clarified using the steady flow. The results indicated that the apparent gap was different between cylinders and pipes and was in propotion to the water level difference. Next, the evaluation method by using the numerical simulations were verified to apply to the ports with complex shape using a real-scale virtual water channel. According to the results, the protection performance was affected by the size of the port and the height of waves and could be estimated by the rough estimation method.

DOI： 10.2208/kaigan.75.i_805

CiNii Research

researchmap

Other Link： https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17H01293/

Language：Japanese   Publisher：Japan Society of Civil Engineers  

In considering the secondary damage of a tsunami, it is important to consider whether a container placed in a port will collide with structures behind in the run-up tsunami wave. Therefore, we conducted a hydraulic experiment to investigate the behavior of tsunami debris due to the run-up wave. As a result, not only the run-up wave but also the reflected wave generated by the structure behind was important that we examine the drift of the tsunami debris. Therefore, we examined the influence of the impinging distance into the the reflected wave on the drift behavior by changing the initial position, initial angle, and weight of the tsunami debris. We confirmed that the impinging distance into the reflected wave had a significant effect on the impinging speed of the reflected wave, the collision speed at the reflection wall, and the probability of collision at the reflection wall. The probability of collision decreased because the impinging distance into the reflected wave increased as the distance from the initial placement of the tsunami debris to the reflection wall increased. Furthermore, when numerical calculations were used to perform analysis for a part of the experiment, the results were almost consistent with the results of the experiment.

DOI： 10.2208/kaigan.75.i_439

DOI： 10.3390/jmse9050493_references_DOI_5dzxMYHkbvCBAmSg72PH5FNsGZs

CiNii Research

researchmap

Other Link： https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17H01293/

Language：Japanese   Publisher：Japan Society of Civil Engineers  

To evaluate the performance of wave dissipation structure, cross-sectional experiments has been performed to measure the reflectance coefficient. However, this method is insufficient, because waves sometimes propagate to a dissipating wave structure in the oblique direction. In constant, in an experiment using a plane water tank, multiple reflections of waves are generated. Thus measuring the flow velocity and wave height is difficult, so that. The experimental conditions that can be examined are limited. Therefore, we studied the oblique incident based on numerical calculation. The results of numerical calculation were generally consistent with the measured values in our experiment. Thus, it is expected that overtopping at oblique incidence using numerical calculation in the future.

DOI： 10.2208/kaigan.75.i_775

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

We focused on the information of tsunami inundation and GIS obtained before the initiation of evacuation in order to evacuate evacuees to evacuation facilities smoothly. In this study, we examined effects of prior information of tsunami arrival time and road blockage against the evacuation. Moreover, we evaluated the vulnerability of the city against tsunami based on the heavily-used route and the death rate at evacuation start position. By giving tsunami inundation information and GIS information to the evacuees as prior information, evacuation without death due to a tsunami encounter and re-searching road due to its blockage were suceeded. We conducted the simulation using this method at Nakatosa, Kouchi prefecture, then confirmed that the dearh rate of evacuees which started evacuation immediately after the tsunami arrival time was reduced. Moreover, using our method, we revealed that there are differences in use rate of evacuation route. We also confirmed that death rate become high in the areas that many road obstructions are existed.

DOI： 10.2208/kaigan.75.i_1357

CiNii Research

researchmap

Other Link： https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17H01293/

Language：Japanese   Publisher：土木学会  

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publishing type：Research paper (bulletin of university, research institution)  

Two category 5 hurricanes were passed near US Virgin Islands in the summer of 2017. The post-disaster survey of Hurricane Irma and Maria in 2017 was conducted by Japan-US joint survey team in US Virgin Islands (USVI). The severe coastal damage including inland inundation, wave run-up and wind induced damage was observed in three islands of St. Thomas, St. John and St. Croix in USVI.

CiNii Books

CiNii Research

researchmap

Other Link： http://hdl.handle.net/2433/235765

Language：Japanese   Publisher：日本建築学会  

CiNii Books

CiNii Research

researchmap

Publishing type：Research paper (international conference proceedings)  

© 2018 American Society of Civil Engineers (ASCE). All rights reserved. ♦ Overall Goals ■ Successful mission to document Irma/Maria storm surge in USVI ■ Documented several examples of damage to built environment ♦ Drone survey data ■ Qualitative data o relatively cheap, easy o requires some planning ■ Quantitative data o Requires additional equipment & time for ground control points o Requires post processing, expertise ♦ Data sharing (images) ■ Phone apps (eg FULCRUM) o relatively cheap, easy o requires cell/internet eventually o Excellent for short metadata description, geolocation

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：FUJI TECHNOLOGY PRESS LTD  

On September 28, 2018, following a magnitude 7.5 strike-slip fault earthquake, an unexpected tsunami inundated the coast of Palu bay, Sulawesi, Indonesia, causing many casualties and extensive property damage. However, the earthquake's mechanism rarely generates a destructive tsunami. The tidal record at Pantoloan, located along the coast of Palu bay, indicates that the tsunami arrived 6 min after the earthquake and generated 2 m of receding water. It had a maximum wave height of 2 m and arrived approximately 2 min later. The tsunami had a relatively short period and caused devastation as far inland as 300 m. Additionally, 8 m high watermarks were observed near the coast; the flow depth decreased to 3.5 m inland (Fig. 1). Amateur videos and eyewitness accounts indicate that the tsunami did not enter the bay through its mouth but obliquely from an area inside the bay. Our hypothesis, therefore, is that the killer tsunami was most likely generated by an underwater landslide occurring inside Palu bay. While detailed bathymetric data are still needed to confirm this hypothesis, in this article we provide a preliminary analysis of the available data, supported by the results of a field survey, to strengthen this hypothesis and provide direction for further post-tsunami surveys and analysis.

DOI： 10.20965/jdr.2018.sc20181108

Web of Science

researchmap

Publishing type：Research paper (scientific journal)  

CiNii Research

researchmap

Publishing type：Research paper (scientific journal)  

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

In this research, the accuracy and computational efficiency of gas-liquid two-phase fluid simulation were focused. For the estimation of the impulsive force acting on the upright wall, calculation precision was improved by applying a complete windward difference to the gas phase region and a difference scheme corresponding to the volume fraction of the fluid of each element in the gas-liquid mixture region. For computational efficiency, the computation time was reduced by eliminating the dependency between elements during forward substitution and backward substitution processing in the matrix solution and hybrid parallelizing it together with region segmentation method.

DOI： 10.2208/kaigan.74.i_1039

DOI： 10.2208/kaigan.76.2_i_787_references_DOI_EWkitiCbHVR8YE9EQQhGbZE5Uxu

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/029326965

Language：Japanese   Publisher：Japan Society of Civil Engineers  

In this study, factors causing the underestimation of morphological changes due to tsunami-induced sediment transport in Kesennuma Bay with narrows during the Great East Japan Earthquake and Tsunami have been numerically investigaed. Based on the estimation, the saturated concentration of suspention model was improved. It was found out that strong unsdeady flows occerred at narrows. The numerical results from conventional saturated concentration model implied that at the narrows, suspension concentration and sediment supply from the bottom to the suspension were limited by high concentration in suspension, leading to underestimation of morphological change, i.e., erosion and deposition. By considering effects of strong unsteady flows on concentration of suspention, a new form of saturated concentration model based on log-wake law and Kármán constant theory has been proposed. Numerical results of the erosion and deposition in Kesennuma Bay were improved. It is expected that accuracy of evaluation about not only morphological changes but also inundation area and damages are improved.

DOI： 10.2208/kaigan.74.i_325

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/029324989

Language：Japanese   Publisher：Japan Society of Civil Engineers  

In this study, we conducted inundation calculation of multiple tsunami sources with tsunami simulation and constructed the database of tsunami arrival times considering uncertainty of tsunami sources and aimed to propose a method to search evacuation routes not encountering the tsunami. The tsunami risk on evacuation route calculated by tsunami database, and evacuation behavior to select evacuation route that does not encounter the tsunami was incorporated into multi agent simulation. As a result, the method of selecting a route that does not encounter the tsunami during the evacuation behavior was established by changing the moving direction to the direction of the shortest distance of another evacuation shelter when there is a possibility of encountering a tsunami during the evacuation behavior calculated from the degree of danger. The area was simulated by this method, and confirmed that the mortality rate was reduced.

DOI： 10.2208/kaigan.74.i_397

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/029325096

Publishing type：Research paper (international conference proceedings)  

Scopus

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

The recent 2011 off the Pacific coast of Tohoku Earthquake earthquake and tsunami generated huge tsunamis, and many protective facilities were destroyed. Most of the damage was caused by tsunami overflow. After a main shock occurred, many aftershocks occurred. As for the possibility that a structure suffered from by the superposition phenomenon of an earthquake and the tsunami, it is thought. A large-scale hydraulic model experiment was conducted to confirm it about the influence on breakwater in the superposition of an earthquake and the tsunami, and residual horizontal displacement. In superposition of an earthquake and the tsunami of the breakwater, it was affected by the tsunami and confirmed that different residual displacement was produced only in the case of an earthquake. As a result, at an earthquake and the compound action of tsunami overflow, it clarified that there was a tendency to reduction effect of the acceleration and increase of the horizontal displacement.

DOI： 10.2208/jscejseee.73.i_479

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

In this study, we applyed Dupuit-Forcheimer's law to the processing of the fluid side porosity of CADMAS-STR. The result were compared with the result of physical experiments. It was found that the calculation and the experiment result showed consistent value for the seepage flow velocity under the sheet pile. The validity of this method was therefore confirmed. In addition, pore water pressure was consistent with the calculation and the experiment. From this result, it was found that reproducing the seepage flow velocity by applying Dupuit-Forchheimer's law, it is possible to estimate pore water pressure exerted by underground water.

DOI： 10.2208/kaigan.73.i_1111

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/028755801

Language：Japanese   Publisher：Japan Society of Civil Engineers  

Water cycle facilities are usually constructed at coastal area because of sewage collecting system by gravity flow. So, seismic performance against not only earthquake motion but also tunami should be secured. In this study, we have proposed isolation structural method against strong earthquake motion and wave force of tsunami by utilizing asphaltic viscous fluid isolator. Effectiveness of the proposed method was examined by three-dimentional FEM analyses. As a result, it is considered that stress within the structure induced by earthqauke motion and tsunami can be largely reduced by buffer effect of isolator.

DOI： 10.2208/jscejseee.73.i_721

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

The purpose of this study is to clarify the effect of different protective facility damage levels on tsunami inundation. We developed a method to evaluate tsunami inundation using a fragility curve that represents the relationship between tsunami height and facility damage levels. The adequate results were obtained as the results of carrying out the test calculation and the real scale calculation. In addition, because comparisons of the calculation result actually lowered the top end height of the protective facility, it was found that the result is similar to the reduction of the top end height by about 30%.

DOI： 10.2208/kaigan.73.i_337

DOI： 10.20965/jdr.2019.p0212_references_DOI_Q5rUNnGmfsPJoNS2Pk6V5GjTPKW

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/028749596

Publishing type：Research paper (scientific journal)  

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

The purpose of this study is to clarify how much vertical telescopic breakwater affects water level reduction in the event of a storm surge for the development of an evaluation method by using CADMAS-SURF/3D and STOC-ML. The velocity flow between the breakwaters corresponds to the theoretical value, which is evaluated based on water level difference. Therefore, the result indicates that the aperture can be reduced by around 1.0% when analyzing the breakwater with 7.2% aperture using STOC-ML. Because of this study, it is possible to obtain approximate water level reduction using dimensionless quantities including the conditions of wave, breakwater, and harbor.

DOI： 10.2208/kaigan.73.i_235

DOI： 10.2208/kaigan.77.2_i_823_references_DOI_1QRvVG27x6VSuRYsKwPcMkCUaTB

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/028749381

Language：Japanese   Publisher：Japan Society of Civil Engineers  

In this study, the tsunami risk on evacuation route calculated by calculating tsunami behaviors of relatively large scale using the tsunami simulation in advance, and evacuation behavior to select evacuation route that does not encounter the tsunami was incorporated into multi agent simulation. As a result, the method of selecting a route that does not encounter the tsunami during the evacuation behavior was established by changing the moving direction to the direction of the shortest distance of another evacuation shelter when there is a possibility of encountering a tsunami during the evacuation behavior calculated from the degree of danger. The area was simulated by this method, and confirmed that the mortality rate was reduced.

DOI： 10.2208/kaigan.73.i_1501

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/028756997

Language：Japanese   Publisher：Japan Society of Civil Engineers  

GSM (Global Spectral Model). A climate distribution data set by JMA (Japan Meteorological Agency) is applied to the wave and storm surge estimation for explosive cyclones and typhoons. Wind and atmospheric pressure conditions for the wave and storm surge estimation are obtained using two methods involving the GSM data set. One way is that the GSM data set is linearly interpolated while another is an empirical typhoon model based on the data set. The main results are summarized as follows; when linear interpolation is used in estimations of meteorological fields, it shows high correlation with long-term waves due to bomb low pressure. On the other hand, when using a typhoon model to estimate the weather field, it was confirmed that this method yields high accuracy to the peak value of local typhoon-generated waves.

DOI： 10.2208/kaigan.73.i_145

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/028749121

Language：Japanese   Publisher：Japan Society of Civil Engineers  

An integrated tsunami model consisting of models for simulating tsunami inundation, drifting objects and sediment transport, was newly developed to evaluate the effects of these multiple phenomena. A scenario of complex tsunami damage enlargement in a bay with bottleneck was revealed. The tsunami hazards in Kesennuma City, especially at the inner part of the bay such as Shishiori area, were enlarged by erosion in the bottleneck of the bay. The bathymetric change increased the drift distance of the drifting vessels. In addition, through the tsunami fragility functions based on dataset of actual damaged building and numerical results, it was evaluated that the 200 - 1,800 wooden buildings were washed away owing to sediment transport. Furthermore, it is found that the estimation accuracy of damage scale by the conventional fragility functions was suitable, although the estimated building damage near the sea and inland was under and overestimated, respectively.

DOI： 10.2208/kaigan.73.i_355

DOI： 10.20965/jdr.2021.p1045_references_DOI_7SXqLFNp3AF7qbdA57XejQHBmTV

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/028749636

Language：Japanese   Publisher：Japan Society of Civil Engineers  

The purpose of this research is to develop STOC-CADMAS-STR system, which is numerical fluid simulator coupling with the structure analysis to efficiently calculate all stages from tsunami source to runup including the deformation of structures. We also investigated the stability of breakwaters at K port. The numerical results were compared with the physical experiments. It was good agreement with the experimental ones. Finally, the system applied to the local situation at K port to verify its applicability. The most breakwaters were washed away, whose situation was similar to the damage at K port.

DOI： 10.2208/kaigan.73.i_325

DOI： 10.2208/kaigan.77.2_i_19_references_DOI_BLL0izHVRQlmk2VVHfXuOhjJLuG

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/028749582

Language：Japanese   Publisher：Japan Society of Civil Engineers  

In subduction-zone earthquakes, which cause a tsunami, it is considered that the influence of aftershocks may act on a breakwater even when wave-overtopping is taking place. However, it is unclear what effect the superposition of earthquake and tsunami will have on breakwaters. In this study, a large hydroflume capable of reproducing the superposition phenomenon of earthquake and tsunami was used. The study revealed the influence due to frequency difference and the difference depending on the presence or absence of deformation of the mound.

DOI： 10.2208/kaigan.73.i_1003

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/028752531

Language：Japanese   Publisher：Japan Society of Civil Engineers  

The evacuation behavior of residents in times of earthquake and tsunami is influenced by many factors, including knowledge in disaster prevention, participation in disaster prevention activities, and sensory experience of earthquake shaking. Using survey questionnaire to investigate the evacuation behavior of residents in Iquique during the 2014 Iquique Earthquakes in Chile, this study found that the sensory experience of earthquake shaking is the main factor that prompted residents to evacuate. However it was difficult for elderly persons to evacuate due to shortage of disaster risk. Moreover, the study also found that the location, where the residents live, is an important factor for evacuation. On the other hand, hazard map was found to have little influence on decision of residents to evacuate.

DOI： 10.2208/jscejsp.73.92

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

In recent years, a numerical design for the coastal engineering problem, namely, the so-called numerical wave flume is widely used and expected to expand its potential more as an ancillary or substitute tool for hydraulic experiments. However, for the time being, the numerical wave flume is limited in versatility for the actual engineering problems as the request level of coastal designs is increasing. In this study, a numerical wave flume based on the accurate particle method with a DEM coupling model, namely, parisphere is newly developed for accurate and stable simulations of the violent free-surface multiphase flows. First, a simple benchmark is performed by targeting a sedimentation of heavier particles in the water to examine the numerical accuracy of the model. The parisphere shows a good reproducibility in the motions of particles with an improvement of the energy conservation. Second, a simulation of a complex damaging process of a breakwater, which includes solid-liquid multiphase flows, is implemented. By comparing with the experimental results, it is found that parisphere can reproduces the complex phenomenon with satisfying the prudent requirements, that is, expression of solid-solid/solid-liquid interactions, porosity of the mound, drifting of rigid bodies and accurate pressure distributions.

DOI： 10.2208/kaigan.73.i_25

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/028748817

Language：Japanese   Publisher：日本建築学会  

CiNii Books

CiNii Research

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：E D P SCIENCES  

In 2011, the example that breakwaters collapsed because of the basic ground's destabilization was reported by Tohoku-Kanto earthquake tsunami. Fluid-Structure-Soil coupling simulation is desired for a systematic comprehension of the breakwater collapse mechanism, and it may help to develop next disaster prevention method. In this study, A particle simulation tool based on the SPH has been modified and improved to analyze seepage flow and soil scouring. In seepage flow analysis, as a first step, this simulation treat the surface flow and seepage flow interactions by using governing equation. In the scouring analysis, soil scour is judged by an empirical criteria based on quicksand quantity formula.

DOI： 10.1051/matecconf/20164703019

Web of Science

Scopus

researchmap

Publishing type：Research paper (international conference proceedings)  

When a major earthquake occurs, it can be followed by an incoming tsunami, both of which destroy many structures and cause serious damage. Although the destruction of structures caused by earthquakes and by tsunamis has been studied, the further damage caused by aftershocks after a major earthquake occurring at the time of a tsunami has not been sufficiently reported. In this study, we aimed to determine variations in the influence of different structural shapes when the effects of an earthquake and tsunami are superposed. A sloping structure was shown to reduce the hydrodynamic pressure; even when an earthquake and tsunami occur simultaneously.

Scopus

researchmap

Publishing type：Research paper (scientific journal)  

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

The recent 2011 off the Pacific coast of Tohoku Earthquake earthquake and tsunami generated huge tsunamis, and many protective facilities were destroyed. Most of the damage was caused by the tsunami overflow. On the other hand, many aftershocks occurred after the main shock and attacked the coastal facilities combined with tsunami. In order to clarify the superposition phenomenon of an earthquake and the tsunami, large haydraulic experiments were conducted. As a result, it was clarified that the hydraulic pressure acting on the caisson is basically expressed as a superposition pressure of earthquake and tsunami.

DOI： 10.2208/kaigan.72.i_1057

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/027811182

Language：Japanese   Publisher：Japan Society of Civil Engineers  

The purpose of this study is to clarify the effect of the overflow falling height on the scour depth using physical experiments. Small-scale physical experiments were performed. The results indicate that the maximum scouring depth increases when the falling height of the overflow increases up to a given height. However, the maximum scouring depth decreases if the falling height is greater than the critical height because the diameter of the vortex decreases at such falling heights. The relation between the diameter of the vortex and the maximum scour depth is compared to the formula used in two previous studies. The scour depth determined in this paper is smaller than that estimated by the previously published formula. Thus, it is important to evaluate the velocity on the bottom for accurate estimation of the maximum scour depth.

DOI： 10.2208/kaigan.72.i_1087

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/027811226

Language：Japanese   Publisher：Japan Society of Civil Engineers  

The purpose of this study is to verify the effect of the seawall height on successful evacuation rates. The relation between the height of seawalls and the mortality was analyzed using the data of past questionnaires. Furthermore, numerical tsunami and evacuation simulations were performed for two towns to verify the effect of different seawall heights on morality. Under Tohoku tsunami conditions, the results indicate that early evacuation is more effective in decreasing mortality rates than constructing higher seawalls. The numerical results show that the inundation area decreases by 5% and the mortality decreases by 10 to 20% when the seawall height increased. On the other hand, the mortality rate was reduced to zero when the start time to evacuation is within 10 min.

DOI： 10.2208/kaigan.72.i_1561

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/027813386

Language：Japanese   Publisher：Japan Society of Civil Engineers  

The coastal structure may collapse due to beach erosion and scour. There are few cases that tried to analize the scour of coastal sturucture affected by tsunami. In numerical simulation, a particle method is suitable for tracking complicated surface water motion and sand movement. In this study, we performed the reproducible analysis of the toe scour of a seawall of the large-scale experiment using numerical simulation based on an accurate ISPH method. As a result, it is proved that the waveform and velocity of the first wave are accurate by reproduced. The behavior of scour can also be reproduced by the ISPH method.

DOI： 10.2208/kaigan.72.i_595

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/027809511

Language：Japanese   Publisher：Japan Society of Civil Engineers  

The purpose of this study is to clarify the effect of different protective facility damage levels on tsunami inundation. The facility damage level due to the combination of earthquakes and tsunamis is unknown, so the numerical inundation evaluation methodology is verified using the Monte Carlo method, which is used to determine the seawall damage level. In this study, 942 cases with different seawall damage levels were performed. The results indicate that some areas exist where the maximum inundation height increases by around 30% and the beginning of inundation occurs about 2 min earlier than in the case with no seawall. On the other hand, the inundation area was almost covered in the case with no seawall.

DOI： 10.2208/kaigan.72.i_301

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/027808457

Language：Japanese   Publisher：Japan Society of Civil Engineers  

This study attempts to investigate effect of a tsunami evacuation tower by using evacuation simulator is coupled with tsunami simulator. This simulator calculates the behavior of evacuation and tsunami at the same time. Thus, the difference of the human suffering and the impact on the evacuation behavior were validated. As a result, in this study's conditions, when the evacuation tower was established at the location near coastal area, it was confirmed possibility to encounter tsunami rises depending on the evacuation start time. On the other hand, when evacuation starts earlier than tsunami arrival time, it was confirmed that it is possible to significantly reduce the death rate. Finally, the effect of new tsunami evacuation tower was validated. As a result, it was confirmed that the death rate is decreased by shortening the average evacuation distance.

DOI： 10.2208/kaigan.72.i_1567

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/027813391

Language：Japanese   Publisher：港湾空港技術研究所  

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：港湾空港技術研究所  

CiNii Books

CiNii Research

researchmap

Language：Japanese  

CiNii Books

CiNii Research

J-GLOBAL

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

In 2011, Tohoku-Kanto earthquake tsunami caused serious damage on the port structures such as breakwater and seawall. Damage mechanisms of these structures have been studied in the past, and there are mainly three causes; I. horizontal force due to the water level difference between the front and rear breakwater, II. piping destruction associated with the decline of the bearing capacity by seepage flow and III. soil scour and erosion behind the seawall during overflow. Fluid-Structure-Soil coupling simulation is desired for a systematic comprehension of seawall collapse mechanism, and it may help to develop next disaster prevention method. In this study, a particle simulation tool based on the SPH has been developed to solve soil scour problem. By using the empirical equation based on the correlation between shear velocity and sediment discharge, we implemented the numerical analysis to replicate phenomenon of scouring in the back of breakwater. The experiment tests with 1/25 scale breakwater are utilized for the validation of our numerical simulation model, then we have discussed the applicability and limitation of the empirical equation.

DOI： 10.2208/jscejam.71.i_389

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

This paper presents the experimental studies on the tsunami wave force by using solitary waves. The physical experiments were conducted by using different constant slopes, which are 1/40, 1/20, 1/10 and 0. The results indicated that the pressure coefficient of sustained wave pressure due to solitary waves was described as the square of Froude number and the energy loss of coefficient was obtained as 3.0. The impulsive bore force was 2 to 3 times as the sustained force, even if the condition of occurrence was limited.

DOI： 10.2208/kaigan.71.i_889

DOI： 10.20965/jdr.2021.p1286_references_DOI_MEKSYkNlfaLjFDXiyo7kSb9Jaua

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/027084303

Language：Japanese   Publisher：Japan Society of Civil Engineers  

Wastewater treatment plants are usually constructed at coastal zone and river mouth area because of gravity system for collecting sewage. Consequently, they can be attacked by not only strong motion but also tsunami at earthquake time. In this study, we proposed isolation structural method against strong earthquake motion and tsunami by utilizing asphaltic viscous fluid isolator. Applicability of the method was examined by numerical analyses based on incompressible smoothed particle hydrodynamics. As a result, it is considered that wave pressure induced by tsunami can be reduced due to three-dimensional cushion effect of isolator.

DOI： 10.2208/jscejseee.71.i_235

DOI： 10.2208/jscejseee.73.i_721_references_DOI_LPv7DEIgq82kvYARkNXWl3teQg8

CiNii Research

researchmap

Language：Japanese   Publisher：The Japanese Society of Fisheries Engineering  

The structure of a "tenacious" breakwater is required from the Great East Japan Earthquake in 2011. The widening work is one of existing reinforcement methods of tenacious breakwaters. However, it also has large cross section in port inside area. Furthermore, scouring due to the overflow decreases the bearing capacity of the rubble mound and it makes the breakwater easy to fall down. In "Tsunami-Resistant Design Guideline for breakwaters", by Ministry of Land, Infrastructure and Transport, the widening work is described, on the other hand, the reinforcing method to resist tsunami with steel pipe piles is proposed too. Therefore, we developed the reinforced method of a tenacious breakwater with steel pipe piles. The breakwater has filling stones between the caisson and the steel pipe piles, and it can resist a tsunami tenaciously. We call the method "Steel Pipe method".

DOI： 10.18903/fisheng.52.2_119

CiNii Books

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/026966776

Language：Japanese  

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

In “The 2011 off the Pacific coast of Tohoku Earthquake”, many breakwaters in the coastal areas suffered extensive damage under tsunami overflow. It has been needed to develop the methods of reinforcing the breakwater, tenaciously.<br> The widening work is one of existing reinforcement methods of tenacious breakwaters. But, it also has large cross section in port inside area. Furthermore, Scouring due to the overflow decreases the bearing capacity of the rubble mound and it makes the breakwater easy to fall down. On the other hand, one of the reinforcing methods to resist tsunami, installing a steel wall behind the breakwater, was proposed by Oikawa, et al. (2014). In the series of loading tests, the model caisson on the dry sandy ground wad loaded horizontally. Applying the combination of steel wall and filling between the wall and the caisson improved the horizontal resistance of the caisson effectively. And, this improving method changes the failure mode of the caisson from sliding into ground bearing failure even in scouring cross section.<br> This paper deals with the stability of the breakwater with Steel Pipe Piles by the hydraulic model tests and the analyses. A breakwater cross section (‘O’ port) were used in the tests to clarify the failure mechanism of breakwater with the combination of the wall (composed of steel pipe piles) and the filling, called “Steel Pipe Method” here, under tsunami overflow. The summary is as follows.<br> 1. The experimental results show that “Steel Pipe Method” improves stability of breakwater under tsunami overflow.<br> 2. The main failure modes of the breakwater with “Steel Pipe Method” under tsunami overflow are ‘overturning of steel pipes’.

DOI： 10.2208/jscejoe.71.i_623

CiNii Research

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

DOI： 10.1299/jsmecmd.2015.28._296-1_

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

After The 2011 off the Pacific coast of Tohoku Earthquake, it has become important that not only enhancement of hardware side e.g. construction of seawalls, but devising the comprehensive effective disaster prevention schemes including software measures like establishment of evacuation scheme, according to increase of possible tsunami height. In this study, we develop the evacuation simulator coupled with numerical wave flume e.g. STOC or CADMAS-SURF/3D and looked into the impact of the street pattern and number of evacuation point against evacuation behavior at Kamaishi city and Iquique city, whose street patterns are characteristic, by using this simulator.

DOI： 10.2208/kaigan.71.i_319

DOI： 10.2208/kaigan.77.2_i_241_references_DOI_WzYEY4KXYAFeT57Bd1eDERGxeNK

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/027078207

Language：Japanese   Publisher：Japan Society of Civil Engineers  

In “The 2011 off the Pacific coast of Tohoku Earthquake”, many breakwaters in the coastal areas suffered extensive damage under tsunami overflow. It has been needed to develop the methods of reinforcing the breakwater, tenaciously.<br> One of the reinforcing methods to resist tsunami, installing a steel wall behind the breakwater, was proposed by Oikawa, et al. (2014), called “Steel Pipe Method” here. In the series of loading tests, the model caisson on the dry sandy ground wad loaded horizontally. Applying the combination of steel wall and filling between the wall and the caisson improved the horizontal resistance of the caisson effectively. And, this improving method changes the failure mode of the caisson from sliding into ground bearing failure even in scouring cross section. And the hydraulic model tests and the analyses was conducted by Arikawa, et al (2015). The experimental results show that “Steel Pipe Method” improves stability of breakwater under tsunami overflow.This paper deals with the stability of the breakwater installing “Steel Pipe Method”, which can be examined from quantitative dynamic equilibrium.

DOI： 10.2208/kaigan.71.i_1093

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/027091517

Language：Japanese   Publisher：Japan Society of Civil Engineers  

In this study, firstly, we clarified force to act on a bridge girder under steady flow by physical experiments. Next, we calculated velocity to act on the bridge girder by tsunami run up analysis using STOC, and predicted the damage of bridge girder. From the result of the physical experiment, we suggested a formula for computation of a drag coefficient and the lift coefficient under conditions of the steady flow. We performed tsunami run up analysis for bridges of the tsunami inundation area to get velocity to act on bridge girder and water level elevation.We performed the damage prediction of the bridge by empirical formula of a drag coefficient and the lift coefficient and velocity by tsunami going up analysis. As a result, the predictive precision improved more as a result of past by using this technique.

DOI： 10.2208/kaigan.71.i_955

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/027085519

Language：Japanese   Publisher：Japan Society of Civil Engineers  

At The 2011 off the Pacific coast of Tohoku Earthquake, many seawalls were damaged by Tsunami overflow. Some previous studies indicated that if the foundation of structures was scoured, the stability of structures seriously declined, but the relationship between scouring depth and overflow hasn't been well understood and prediction method hasn't also established. In this study, the scouring depth caused by tsunami overflow was calculated by using numerical simulation based on accurate ISPH method and the results were compared with the physical model tests. The results of this study are as follows; 1) There is a high proportional relationship between scouring depth and the overflow depth, 2) The scouring behind the seawall can be reproduced and the maximum scouring depth can be evaluated by accurate ISPH method.

DOI： 10.2208/kaigan.71.i_253

DOI： 10.2208/kaigan.72.i_1087_references_DOI_TEhce3NsjMz6XIlakKxuBnbvH4s

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/027077870

Language：Japanese   Publisher：土木学会  

A numerical wave flume based on a particle method is a key tool for a design of coastal structure under the action of extremely large and strongly nonlinear wave forces. The SPH, which is the predominant method in the international research society, contains unphysical artificial viscosity due to its explicit algorithm. The ISPH method evades the artificial viscosity by introducing semi-implicit algorithm, however it suffers from another drawback, namely a pressure fluctuation. In this study, accurate schemes, which have been developed to enhance a stability of pressure in the MPS method, are applied to the ISPH method, with examining their applicability through some benchmark tests.

DOI： 10.2208/kaigan.70.I_21

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

In this report, the effectiveness of decreasing of tsunami force due to seawall was investigated by physical experiments. The seawall with 30cm height was used in this study, and solitary waves and sin waves were attacking on the building behind the seawall. Three different situations of seawall were tested. One is without seawalls, the other is with seawalls, and those seawalls are falling or rigid. The results show that the relationship between the Froude number and the coefficient of pressure are based on the Bernoulli's principle. When the tsunami height is almost same as the height of seawall, the pressure on the buildings behind seawalls are getting smaller than that without seawalls. The speed of falling of seawall is affected on the pressure on the building. If the speed is getting higher, then the pressure is getting larger.

DOI： 10.2208/kaigan.70.I_806

CiNii Books

CiNii Research

researchmap

Other Link： https://jlc.jst.go.jp/DN/JALC/10041330431?from=CiNii

Language：Japanese   Publisher：土木学会  

After 2011 Tohoku-Oki Earthquake, construction of seawalls with tenacious structure is needed, but there are few studies about change of tsunami force acting on buildings behind the seawalls according to construction of them. So in this study, we looked into the applicability of CADMAS-SURF/3D to calculate tsunami force through reproduction calculation of physical model experiment which was conducted by Arikawa and Oie (2014), and consider about change of tsunami force according to seawalls condition. The results of this study are as follows; 1) The tsunami force acting on buildings behind the seawalls is well reproduced with CADMAS-SURF/3D, 2) Depending on the distance from seawalls, some cases with seawalls have bigger coefficient of pressure α than the cases with no seawalls.

DOI： 10.2208/kaigan.70.I_801

CiNii Books

CiNii Research

researchmap

Other Link： https://jlc.jst.go.jp/DN/JALC/10041330424?from=CiNii

Language：Japanese   Publisher：土木学会  

In this paper, responses of a pontoon in tsunami were studied. As an example, a pontoon by the mooring pile system of Izushima fishing port in Miyagi Pref. was treated. The pile of the pontoon was pulled out of the tsunami which was derived from the Great East Japan Earthquake. Model tests in a solitary wave was carried out and tsunami simulation was also carried out. The pontoon was capsized in fast elevating cases of water surface. In order to suppress the capsizing, it is effective to place the roller fender lower than the gravity center to increase restoring moment. According to the tsunami simulation for Izushima fishing port, tsunami height was small enough compared to the wave length and elevation speed was slow. Thus, the pullout force of the pile is estimated mainly from surplus buoyancy, and capsizing should not be occurred.

DOI： 10.2208/kaigan.70.I_906

CiNii Books

CiNii Research

researchmap

Other Link： https://jlc.jst.go.jp/DN/JALC/10041330653?from=CiNii

Language：Japanese   Publisher：土木学会  

Many breakwaters were damaged by the Great East Japan Earthquake of March 11, 2011. Many of these were destroyed under tsunami overflow. Some results of researches indicated that in the case where scouring of the foundation had occurred, the safety factors for bearing capacity failure declined to less than in a case where the foundation part was not scoured. But, the relation between the overflow and scouring depth had not been clarified. In this study, the scouring depth due to tsunami overflow was investigated by using the physical model tests. Results pointed out that the scouring depth can be evaluated by the scale of vortex due to overflow.

DOI： 10.2208/kaigan.70.I_926

CiNii Books

CiNii Research

researchmap

Other Link： https://jlc.jst.go.jp/DN/JALC/10041330707?from=CiNii

Language：Japanese   Publisher：土木学会  

Leaning revetment is a common type of seawall structure. In common cases, armor blocks and foot protections are placed in front of their lower part. Main purpose of the blocks is to prevent rubble foundation sucking away in high wave condition. However, previous study indicates that these blocks prevent sudden displacement of leaning revetments. In this study, experiments were conducted to measure effect of the blocks to prevent leaning revetments' displacement. The result of the experiments indicated that these blocks have functions: they help to increase stability of leaning revetment's structure including rubble backing if the blocks have abundant weights, they could be evaluated in calculation of stability of leaning revetments, offshore direction force which they receive by a leaning revetment may change under their placed condition.

DOI： 10.2208/kaigan.70.I_936

CiNii Books

CiNii Research

researchmap

Other Link： https://jlc.jst.go.jp/DN/JALC/10041330721?from=CiNii

Language：Japanese   Publisher：土木学会  

One of the possible basic structural countermeasures taken for a breakwater to protect foundation mound and seabed against scouring caused by overflow is widening work for increasing the height of the foundation mound behind the breakwater. The widening work behind the caissons is topped with scour prevention work and a revetment to provide scour resistance to the structure. But the stability of armour blocks on the widening works is not cleared. In this report, the physical experiments were conducted to make clear the mechanism of failure of armour blocks under overflow of tsunami, and to consider the estimation methodology of stability of armour blocks. The results indicated that the stability of blocks related with the porosity of blocks and was estimated by using Isbash equations.

DOI： 10.2208/kaigan.70.I_941

CiNii Books

CiNii Research

researchmap

Other Link： https://jlc.jst.go.jp/DN/JALC/10041330738?from=CiNii

Language：Japanese   Publisher：土木学会  

In ports damaged by Tsunami after The 2011 off the Pacific coast of Tohoku Earthquake, secondary damages were occurred by collision of drifting objects such as container. To reduce those secondary damages, it is important to predict the drifting-motion. In this research examining mechanisms of drifting container, at first, physical experiment was conducted using solitary wave. Then, numerical experiment was conducted under the same conditions using "Solid-Gas-Liquid Coupled CADMAS-SURF/3D". At last, the model applicability was evaluated. In conclusion, the results showed that, in the experimental conditions of this study, this model can be applied to the simulation of container drift.

DOI： 10.2208/kaigan.70.I_331

CiNii Books

CiNii Research

researchmap

Other Link： https://jlc.jst.go.jp/DN/JALC/10041329381?from=CiNii

Language：Japanese   Publisher：土木学会  

After 2011's tsunami , there are a few physical experiments on the stability verification of breakwaters under overflow. These results indicated that the unstability of caisson increases as the difference of water level between front side and rear side increases. The estimation formula for the lateral force under the overflow was also submitted under the limitation number of experiments. The applicability of this equation is not clear. So, in this paper, the applicability of empirical formula is verified by using the numerical simulations. The results indicated that the empirical formula could estimate the stability as the safety side. Through the numerical tests with various shape of the cassions, the device such as parapet or something make the lateral force decreasing because of increasing the vertical force at the crown or increasing the supporting force at the rear side. The economical shape of caissons can be designed against the overflow.

DOI： 10.2208/jscejoe.70.i_366

CiNii Research

researchmap

Language：Japanese   Publisher：港湾空港技術研究所  

CiNii Books

CiNii Research

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier  

researchmap

Language：Japanese   Publisher：日本計算工学会  

CiNii Research

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：World Scientific  

DOI： 10.1142/s0578563414500065

researchmap

Language：Japanese   Publisher：Japan Concrete Institute  

This paper gives an overview of the damage to bridges caused by the 2011 Tohoku Earthquake Tsunami Disaster and its characteristics, and then goes on to verify the extent to which the existing bridge stability evaluation formula is applicable, based on the damage data for the bridges in the tsunami inundation areas.

DOI： 10.3151/coj.52.1059

CiNii Books

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/025953498

Language：Japanese   Publisher：The Japan Institute of Marine Engineering  

DOI： 10.5988/jime.49.350

CiNii Books

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/025518232

Language：Japanese   Publisher：Japan Society of Civil Engineers  

We ported CADMAS-SURF/3D program into a CUDA-MPI hybrid parallel application to achieve further enhancement in execution speed, and studied it's characteristics. By eliminating the data rearrangement overhead remained in the previous paper, we achieved 800% relative speed in single process execution. By utilizing CUDA runtime enabled MPI library, we found that the porting was quite simplistic and straight forward. Even though we verified all variable contents at runtime to justify the algorithm equality between CUDA and FORTRAN, we encountered instability in computation results. But some cases indicated that further speed enhancement was quite possible with hybrid parallelism.

DOI： 10.2208/jscejoe.70.i_361

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

The effects of the wind, the storm surge, and the waves of Typhoon 1330 (Haiyan or Yolanda) were surveyed at Tacloban Port and Airport on Leyte Island and at several ports on Panay Island, Philippines. The windows and roofs of the port office buildings were broken owing to intense wind at the majority of the ports. The ground floor was flooded by only the storm surge or by the storm surge and the waves, at Tacloban, Estancia, Caticlan, and Lipata Ports. The wave-induced damage of the wharf was severe at Estancia and Lipata Ports. The containers and the mooring ships were drifted at Tacloban, Estancia, and Culasi Ports by the wind, the storm surge, or the waves. The information obtained through hearing investigation is useful for the calibration of numerical hindcasts.

DOI： 10.2208/kaigan.70.I_1436

CiNii Books

CiNii Research

J-GLOBAL

researchmap

Language：Japanese   Publisher：土木学会  

Seawalls play a very important role in protecting Japan's coastline, but they may sometimes be destroyed by high waves. The leaning revetment is a common type of seawall structure. The modes of destruction of the leaning revetments were classified into two types: sliding of the bottom of the revetment bodies in the offshore direction, and joint fracture. However, factors which choose each destruction mode were unknown. In this study, experiments were conducted to inspect destruction processes of leaning revetments and its factors in putting emphasis on behaviors of revetments' bodies. The results of the experiments indicated that blocks in front of revetments might restrain sharp sliding of revetments' bodies, and a joint fracture might occur if an impulsive wave force acted on a revetment in particular conditions.

DOI： 10.2208/kaigan.69.i_931

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

In the initial report on a tsunami disaster in the Great East Japan Earthquake, a scouring at a joint between caissons was listed up as one of the causes of failure of a composite breakwater. Although posterior experiments proved that it was not crucial mechanism, a flow field behind a caisson was not investigated in detail in those experiments. In this study, to clarify a complicated flow field driven by jet from a joint and tsunami overflow, we carry out a numerical simulation by using a numerical wave flume based on an accurate particle method. Especially, we focus on a three-dimensional flow structure around a joint between caissons.

DOI： 10.2208/kaigan.69.i_886

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

A large number of breakwaters were damaged by the Great East Japan Earthquake on March 11, 2011. Many were destroyed by tsunami overflows. In this research, physical experiments were conducted using various breakwater cross-sections to clarify the exact failure mechanisms caused by tsunami overflows. Using the experimental results, the cause for the breakwaters' collapse can be verified using the safety factor of sliding, overturning and bearing capacity of each breakwater. If the overflows scoured the rubble mound, the safety margin was estimated using a post-scouring cross-section. Scouring by overflows decreases the rubble mound's bearing capacity, increasing the likelihood that breakwater would collapse. When the scouring reaches the bottom of the caisson, it generates a hole that the caisson gradually falls into.

DOI： 10.2208/kaigan.69.i_916

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

In this research, the hydraulic model experiment examined the power generation efficiency of the caisson furnished with PW-OWC type wave power generation equipment. OWC type wave power generation equipment has established the air chamber in which the portion submerged in water carried out the opening in the front of caisson. The problem is that the primary conversion efficiency of energy will decrease rapidly if the period of a wave separates from a resonance period. Therefore the wall called a projecting wall in the normal line right-angled direction was installed in the front of an air chamber. The primary conversion efficiency of energy of OWC breakwater with PW is larger about 10%. that without breakwater.

DOI： 10.2208/kaigan.69.i_1306

DOI： 10.2208/jscejoe.72.i_802_references_DOI_3xEqU9r3oN8J19IteCSZeSl2zWW

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

In this research, the stability of the quay is examined by hydraulic model experiments at the time of the back rush of overflow tsunami. As a result, by taking earth pressure in back into consideration, it makes clear that the collapse phenomenon of a quay is a slide due to water level difference between front and rear side of a quay. The value of pressure of front side, which is in contact with the rubble ground, has dispersion. This dispersion has influenced stability of a quay and it is producing variation in failure of a quay. Moreover, in order to abolish the variation in the pressure, when it verified using the front water level, it turned out that stability is verifiable to a safe side. In the range of this experiment, it is possible to verify the stability of a quay by applying this assumption.

DOI： 10.2208/kaigan.69.i_971

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

This study is an investigation of the mechanism of the washout of bridge girders by tsunamis, performed by conducting 1/10 scale model experiments and numerical calculation for the case of the Numata Overpass. First, the flow experiment conducted. It confirmed that the flow velocity below the bridge girder is higher than the flow velocity above the bridge girder, applying downward force on the bridge girder. Therefore, the result was that the bridge girder was stabilized by increasing resistance to the flow. Next, the solitary wave experiment confirmed that a lift force caused by fluctuation of the water surface washed out the bridge girder. Finally, CADMAS-SURF 3D replicated the experiments numerically and confirmed the validity of the calculations.

DOI： 10.2208/kaigan.69.i_911

DOI： 10.2208/journalofjsce.7.1_43_references_DOI_HikF04Z8Gm58tmi9dSJzFUF3nC4

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

The measure of floating objects is regarded as important to reduce the second damage caused by tsunami, but there is little knowledge about measures. In this research, the capture effect of containers is examined by hydraulic model experiments using the tsunami barrier. As a result, when pile pitch is smaller than the width of the container, the outflow rate depends on height of the pile and inundation. In addition, the outflow rate extremely tends to rise when the depth of the inundation more than a half of the height of the tsunami barrier. Thus, it is necessary to secure the height of pile of the degree to double of the inundation height in order to get a high capture effect.

DOI： 10.2208/kaigan.69.i_921

DOI： 10.2208/jscejoe.71.i_713_references_DOI_QJBN4TgeLL9xdRaXX09IFrQTCfp

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

In this study, we investigated damaged situation of floating structures in Miyagi Pref. caused by tsunamis in the Great East Japan Earthquake and it made clear that some structures mooring with pile were flowed away. However, structures mooring with chains were never flowed away. we used a case of Izushima, Onagawa-town to examine a mechanism suffered floating structures that mooring with piles and chains. In the case of pile mooring, from the result of examination, it was estimated that piles were left out by tsunami water level rising. In the case of chain mooring, at the result of numerical calculation using by STOC and mooring simulation, it was found that dredging anchor blocks became important factor against outflow.

DOI： 10.2208/kaigan.69.i_866

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：港湾空港技術研究所  

CiNii Books

CiNii Research

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Civil Engineering Conference in the Asian Region  

researchmap

Language：Japanese   Publisher：土木学会  

Generally, many models for large-scale hydraulic test are made from steel and concrete, because it is necessary for them to have strength and durability. Therefore, construction managements that contain safety, accuracy, workability and process control similar to site construction are needed. Although engineers should have knowledge for both general laboratory experiment and site works of construction, there have been no manuals for construction of large-scale model. This is a case study for the large-scale model construction process based on construction of 1/6. 67 scale model used for wave test of the wave power generation facility.

DOI： 10.2208/jscejoe.69.I_103

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

We present a new faster GPU computation and algorithm for CADMAS-SURF/3D by a CUDA parallelization techinique on a GPU accelerator "Tesla". In this paper, we examine the CUDA porting tool for GPU computation and suggest a macro code by C preprocessor for CADMAS-SURF/3D originally coded in FORTRAN to be adopted into CUDA C language. Furthermore, we optimize the data access sequence pattern from a profiling result to eliminate the calculation bottleneck. We inspect the legitimacy of the solution by examining the rounding error, and then examine the program tuning by a data sequence access pattern optimization.

DOI： 10.2208/jscejoe.69.I_754

CiNii Research

researchmap

Language：Japanese  

CiNii Books

CiNii Research

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Fuji Technology Press  

researchmap

Language：Japanese   Publisher：港湾空港技術研究所  

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：国土交通省  

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

CiNii Books

CiNii Research

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Multi Science Publishing  

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Support Journal:The International Journal of Protective Structures  

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：土木学会  

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：土木学会  

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Support Journal:The International Journal of Protective Structures  

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Society of Civil Engineers  

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Society of Civil Engineers  

researchmap

Language：Japanese   Publisher：港湾空港技術研究所  

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：港湾空港技術研究所  

CiNii Books

CiNii Research

researchmap

Language：Japanese  

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Concrete Institute  

DOI： 10.3151/coj.50.23

CiNii Books

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/023416011

CiNii Research

researchmap

Language：Japanese  

CiNii Books

CiNii Research

researchmap

Language：Japanese  

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：日本木材加工技術協会  

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

A tsunami generated by an earthquake of Mw 7.7 hit North and South Pagai Islands and Sipola Island of Mentawai Islands lying off the west coast of Sumatra Island. This paper reports results of a joint field survey on the tsunami disasters. In the survey tsunami inundation and runup heights were measured in North and South Pagai Islands, and interview investigation was also conducted to understand people's evacuation action in the islands. Averaged tsunami height was about 6 m in the islands, resulting in many losses of human lives and houses. However, there was a good example of evacuation. A person who heard sound of tsunami approaching run to hill with transmitting information of the tsunami coming to other residents, and therefore all residents could evacuate to save their lives.

DOI： 10.2208/kaigan.67.i_1281

DOI： 10.2208/kaigan.67.i_301_references_DOI_1BaWWUD2uyTgTMNqnCveASOZVac

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

The baymouth breakwater is to protect the port area from tsunamis as well as storm waves. A submerged dike is built at the central opening section of the tsunami breakwater to close the bay mouth as much as possible. Because of narrowness, strong current is expected at the occasion of design tsunami attack. The submerged dike consisting of a rubble mound foundation and a crown caisson must be stable against the strong current. The present paper points out stability of the crown submerged caisson on the basis of the result of experiment and numerical wave tank (CADMAS-SURF/3D), and according to these results, verifies the validity of pressure coefficients calculated from hydrodynamic forces.

DOI： 10.2208/kaigan.67.i_716

DOI： 10.2208/proce1989.50.716

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

Recently, CFD and FEM analysis are being applied to design and disaster measures of port and harbor structures, and various reports have been performed so far. However, there are not many techniques for simulating accurancy good to the iteraction between wavefields and deformation and fracture of structures. So, we improved the system in the past by Arikawa(2009), and developed as a new Fluid-Structure coupled system, CADMAS-SURF/3D--STR3D, which can treat the large scale model and large scale deformation. And we verified the validity of this developed system, comparing with the water tank test in the past.

DOI： 10.2208/kaigan.67.i_771

DOI： 10.20965/jdr.2019.p0225_references_DOI_LP5tu45f4NKkIl2PhcJUPbj9Xtx

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

It is important to develop the Solid-Gas-Liquid coupling system for analyzing the mechanism of failure of structures on land by Tsunami. At first, the numeric wave tank, whose name is CADMAS-SURF/3D, is improved to correspond to two phase incompressible fluid. This two phase flow tank is applied to the impulsive wave pressure problem. As a result, it is confirmed that a numeric noise, which is called Spike Noise, is removed and the accuracy of the result is good agreement with the single phase model. Next step, the coupling system with DEM method is developed. The wall destruction test by fluid is conducted. The appearance of the wall destruction adjusted the large-scale experiment, and the validity of three phase coupling system is confirmed qualitatively.

DOI： 10.2208/kaigan.67.i_21

DOI： 10.20965/jdr.2019.p0225_references_DOI_FQPYAPXtUg18U53U41JbiHxT4uh

CiNii Books

CiNii Research

researchmap

Language：Japanese  

CiNii Books

CiNii Research

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：World Scientific  

researchmap

Language：Japanese   Publisher：沿岸技術研究センター  

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：港湾空港技術研究所  

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：港湾空港技術研究所  

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

The present study aimed to clarify the influence of the driftwood collision to the destruction of the concrete slab due to tsunamis. The applicability of the empirical formula based on Hertz theory was examined by the large scale collision experiments on the concrete slab with timber in the air and driftwood due to tsunami. The duration time calculated by the formula was good agreement with that obtained from the experimental record of the strain gauge when colliding. It indicated that the impulsive force due to drift wood collision could be estimated by using this formula. Moreover, it was clarified that the destructive force on the concrete slab increased by the collision of driftwood compared with only tsunamis.

DOI： 10.2208/kaigan.66.781

CiNii Books

CiNii Research

researchmap

Other Link： https://jlc.jst.go.jp/DN/JALC/00358855048?from=CiNii

Language：Japanese   Publisher：土木学会  

Reliability design of maritime structures based on the deformation level will be one of the most important future design tools. However, it has not been fully applied to actual design since it is very difficult to take the various design condition into account. The present paper points out on the basis of the experimental results in random wave field, the influences of the state of wave-dissipating blocks on the wave pressures at several cross sections of a breakwater, and the stochastic characteristics of obtained data was examined. The random wave experiment data and the regular wave data correspond well when the impulsive wave pressure is not generated, however when the impulsive wave pressure is generated, the wave pressure on still water level of both experiments are greatly different.

DOI： 10.2208/kaigan.66.841

DOI： 10.2208/proce1989.54.841

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

CADMAS-SURF/3D is a three-dimensional numerical wave tank under development which has recently been applied to some studies of wave-structure interaction. However some problems have been pointed out: for example it is difficult to determine the reasonable drag coefficient and grid dependency of resistance is remarkable. In this study we clarified grid dependency of resistance using a conventional resistance calculation method and examined the influence of drag coefficient on wave force. Next the applicability of the CADMAS-SURF/3D with a Dupuit-Forhhimer method was investigated through the comparison between experimental and numerical results of wave pressures acting on the superstructure of sloping breakwater.

DOI： 10.2208/kaigan.66.776

CiNii Books

CiNii Research

researchmap

Other Link： https://jlc.jst.go.jp/DN/JALC/00358855031?from=CiNii

Language：Japanese   Publisher：土木学会  

The purpose of the present study is to newly propose a numerical wave tank by introducing a wave generation source into a CADMAS-SURF/3D and verify the validity of the numerical wave tank. The numerical experiments with the change of the coefficient α, which is related to the strength and extensity of wave generation source, revealed that the most appropriate waves are able to be generated in the case of α=2. The applicability of the proposed numerical wave tank was confirmed by applying it to oblique wave generation problems and comparing the numerical results with the results of the laboratory experiment on wave deformation under Tsunami action.

DOI： 10.2208/kaigan.66.6

CiNii Books

CiNii Research

researchmap

Other Link： https://jlc.jst.go.jp/DN/JALC/00358854638?from=CiNii

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：土木学会  

researchmap

Language：Japanese   Publisher：地震予知総合研究振興会  

CiNii Books

CiNii Research

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：UK Section of PIANC  

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：UK Section of PIANC  

researchmap

Language：Japanese   Publisher：港湾空港技術研究所  

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：東北大学  

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：日本自然災害学会  

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

Reliability design of maritime structures based on the deformation level will be one of the most important future design tools. However, it has not been fully applied to actual design since it is very difficult to take the various design condition into account. The present paper points out on the basis of the experimental results, the influences of the state of wave-dissipating blocks on the wave pressures at several cross sections of a breakwater, and the stochastic characteristics of obtained data was examined. 1) The covering condition of wave-dissipating blocks makes a significant influence of the wave pressure acting on the block layer. 2) When the impulsive wave breaking is generated, wave pressure p1 on the still water level becomes proportional to the square of the wave height. Then the numerical wave flume (CADMAS-SURF/2D) was applied for the covering state of wave-dissipating blocks.

DOI： 10.2208/kaigan.65.816

CiNii Books

CiNii Research

researchmap

Other Link： https://jlc.jst.go.jp/DN/JALC/00347682792?from=CiNii

Language：Japanese   Publisher：土木学会  

This report describes development of the numerical wave tank, called CADMAS-SURF/3D, coupled with the structure analysis based on FEM. The objective of this research is to clarify the stability of this numerical system. In this system, FEM receives the pressure from CADMAS, on the other hand CADMAS uses the porosity changed from displacements of structures. At first, wave paddle model was tried for confirming the stability of variation of porosity. The results of numerical waves were good agreement with the results of experiments. Then, coupling model was tested by using the wall and sea wall model. Through these results, the stability of this numerical system was verified.

DOI： 10.2208/kaigan.65.866

CiNii Books

CiNii Research

researchmap

Other Link： https://jlc.jst.go.jp/DN/JALC/00347682891?from=CiNii

Language：Japanese   Publisher：土木学会  

The rubble mound of composite breakwaters is usually covered with armor stones or armor concrete blocks. However the damage of armor units is almost appeared at the breakwater head. The minimum weights of the armor units at the breakwater head is 1.5 times the value of the breakwater trunk. This paper aims to elucidate the damage mechanism of armor units at the breakwater head of a composite breakwater by numerical simulation with a 2 or 3-dimensional numerical wave tank `CADMAS-SURF' under regular wave action. Numerical results are compared with experimental data. At the last, the numerical wave tank is applied to real disaster of the armor units of the composite breakwater.

DOI： 10.2208/kaigan.65.861

CiNii Books

CiNii Research

researchmap

Other Link： https://jlc.jst.go.jp/DN/JALC/00347682884?from=CiNii

Language：Japanese   Publisher：土木学会  

A new type structure of break water head covered with wave dissipation blocks was proposed to slash the construction cost. This structure is simply to set a caisson with longer width than a trunk caisson, which can decrease the number of wave dissipation blocks by making use of the longer end-wall of the head caisson. Three dimensional hydraulics model tests were carried out to solve various technical issues regarding the stability and safety of this structure. It was clarified that the current design standard of port facilities is partially applicable to determine the structural dimension, and careful attention must be paid to the depression of crown height of wave dissipation blocks.

DOI： 10.2208/kaigan.65.811

CiNii Books

CiNii Research

researchmap

Other Link： https://jlc.jst.go.jp/DN/JALC/00347682785?from=CiNii

Language：Japanese   Publisher：港湾空港技術研究所  

CiNii Books

CiNii Research

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：World Scientific  

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Fuji Technology Press  

researchmap

Language：Japanese   Publisher：セメント新聞社  

CiNii Books

CiNii Research

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Session Stream C Hydrodynamics  

researchmap

Language：Japanese   Publisher：港湾空港技術研究所  

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：沿岸技術研究センター  

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

The following improvements on tsunami damage predicting are examined in order to decrease the tsunami damage: 1) It is checked that the destructive evaluation of buildings of a wide area due to tsunami can be efficiently performed with the numerical model which can calculate a flood of only land area with good accuracy and the gate type Rahmen model. 2) The limit of inundation height that human-beings can stand up to tsunami is obtained using data of a large-scale model experiment. This limit is determined by a slide and changes in the range of 20cm-40cm with sex and height. 3) When the overflow of tsunami occurs on the land area of a steep slope, a strong back-flow will occur. Therefore, a calculating method which can be used for the stable examination against it is also proposed.

DOI： 10.2208/proce1989.55.301

DOI： 10.2208/kaigan.67.72_references_DOI_9JG9x4sjwlVhWWhSbyqXv9aZ1Uq

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

The Solomon Islands Earthquake Tsunami was generated by a big earthquake of M8.1 on 2 April 2007, and caused severe damages particularly in western islands of the Solomon Islands, resulting in the death toll of 52. To understand tsunami characteristics and damages, a field survey was conducted. Measured tsunami inundation height was approximately 4-5 m at the north part of Simbo Island and at the south coast of Ghizo Island. Human losses were, however, mitigated by residents' evacuation to hills and high-floored houses soon after the earthquake occurrenceand as soon as they watched the tsunami travelling in the offshore. Numerical simulations were also conducted to estimate and understand the tsunami. The effect of reefs in coastal areas was additionally investigated from the numerical simulations.

DOI： 10.2208/proce1989.55.1406

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

Indian Ocean Tsunami 2004 made us to recognize of the power of the huge tsunami. To clarify the mechanism of failure due to tsunami and to make the assessment tool are important not only for the forecast of damage but also for the evaluation of evacuation towers. If the large tsunami occurs, large impulsive bore force may attack on. the land structure near the coastline. But, the behavior of structures against such power is still unsolved. In this report, the physical model tests are conducted to clarify the mechanism of failure of concrete wall due to the impulsive tsunami power. Several types of concrete walls and brick typ.walls with column are tested. From the results, the failure mode of walls against the impulsive tsunami power was clarified qualitatively.

DOI： 10.2208/proce1989.55.261

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

This report describes the results of the large scale model tests on the buoyancy-driven vertical piling breakwater by using the buoyancy-driven piles. This breakwater consists of rows of steel pip. piles and each pile consists of upper and lower steel pipes. The overall performance of this breakwater has been verified, but the relation between stress and wave power is not cleared at the part of lap joint between upper pipes and lower pipes, at which large stress may be occurred. So, the large scale model tests by using the buoyancy-driven piles were conducted. Main results of this paper are that movement of the upper pile under waves is confirmed and the relationship between the strain at the lap part and the wave power is clarified qualitatively.

DOI： 10.2208/proce1989.55.906

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

This report describes large-scale simulations on impulsive wave pressures using CADMAS-SURF/3D (SUper Roller Flume for Computer Aided Design of MAritime Structure in 3D), which is a three-dimensional numerical wave tankunder development. This code is also adapted to the parallel computing system and multi grid size system. Prediction ofimpulsive wave pressure using empirical formula is one of difficult problems. So, the tool for the practical use is neededto solve this problem. In this report, the validity of this model for predictions of impulsive wave pressures is verified.Large scale simulations are conducted by using the field data and the occurrence of impulsive wave pressures is discussed. At the last, the calculation cost is reported for the practical use.

DOI： 10.2208/proce1989.55.26

DOI： 10.2208/jscejoe.67.i_625_references_DOI_QTQFvTCmXOBoPGmeOxlbwdOHdjV

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

The primary objective of tsunami disaster mitigation is to reduce the casualties. The major cause of the deaths is drowning by tsunami current, especially during evacuation. In the paper, the causes of deaths are discussed through reference to past experiences. A fault tree is presented to summarize the physical danger posed by tsunami waves to the human body, and the personal danger is discussed based on the tree. The stability of the human body against wave front collision and tsunami currents is discussed and threshold conditions are proposed. The time for evacuation is usually very limited and the risk of encountering a tsunami during evacuation is often high. Walking in inundated areas during a tsunami attack is especially dangerous. Vertical evacuation is highly recommended.

DOI： 10.2208/prooe.24.159

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

CADMAS-SURF is a useful numerical model to design maritime structure. Applicability of CADMAS-SURF for predictions of breaking waves or irregular waves has been studied. However, there are not many studies about the wave run-up problems. It is necessary to investigate the applicability of CADMAS-SURF for predictions of wave run-up.<BR>This paper presents an investigation for applicability of CADMAS-SURF for predictions of wave run-up. In order to verify the accuracy of CADMAS-SURF, CADMAS-SURF was applied to several wave run-up conditions. The computational results are compared with the experimental results to show the validity and efficiency of CADMAS-SURF. In order to compare the numerical results using different mesh size, several numerical studies were carried out. The present study proposed the calculation conditions for numerical simulation.

DOI： 10.2208/prooe.24.867

DOI： 10.2208/kaigan.75.i_733_references_DOI_Jb5Mv10gw3tyvDpTmssSPoeeFYc

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

An innovative ‘buoyancy-driven vertical piling breakwater’ is under development to protect harbor facilities against high waves and tsunamis. This breakwater consists of rows of steel pipe piles and each pile consists of upper and lower steel pipes. The movable performance and hydraulic characterisitics of the breakwater have been verified by the large scale hydraulic model tests. In addition, the performance of the breakwater in the sea has to be clarified for its realization.<BR>This paper reports the results of the field experiment by a real scale structure. The results clearly demonstrate that: 1) The fabrication accuracy and the placing accuracy of the steel pipes were excellent; 2) The rising time of the breakwater in the waves was within a few minitues; 3) The transmission mechanism of the wave force from the upper pipe to the lower pipe has been proven; 4) The marine growth around the upper pipe was little.

DOI： 10.2208/prooe.24.93

CiNii Research

researchmap

Language：Japanese   Publisher：港湾空港技術研究所  

CiNii Books

CiNii Research

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Society of Civil Engineers  

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Institute Technology Bandung, Indonesia  

researchmap

Language：Japanese   Publisher：土木学会  

This report investigates the impact force of drifting container due to surge front tsunamis. Because the impact force depends on the material and rigidity of the objects, the 1/5 scale model experiments are conducted with container made of steel and concrete wall. First, effect of the material and rigidity, impact force tests in the air are conducted. Then, the velocity of drifting container is checked. Finally, the drifting container impact force tests due to surge front tsunami are conducted. The empirical formula based on Hertz theory is applied to the impact force results. It indicates that this formula can evaluate the impact force under this report condition.

DOI： 10.2208/proce1989.54.846

DOI： 10.20965/jdr.2021.p1045_references_DOI_XbTgBZ3d926awcpSxcqk7V9pMPt

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

While the research on the deformation-based reliability design of composite breakwaters has been carried out for many years, sliding phenomena including rocking motion have not been carefully examined. In this study, hydraulic model experiments were conducted in a wave flume to investigate the characteristics of wave forces and sliding phenomena of the breakwater caisson. The difference of static friction coefficient and dynamic one should be considered in order to improve the estimation accuracy. Numerical simulation (CADMAS-SURF) can reproduce the time series of wave forces more precisely compared to the practical model used in the current calculation method, especially in deep water area.

DOI： 10.2208/proce1989.54.901

DOI： 10.2208/jscejb.65.246_references_DOI_IWmhrKsSoOfaT1wvjHzMJzpGxJq

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

This report describes advanced deformation scheme for breaking waves, and the results of breaking wave simulation. A three-dimensional numerical wave tank was developed. This code is also adapted to the parallel computing system and multi grid size system, so that the problem is more efficiently solved. This code is called ‘CADMAS-SURF/3D’(SUper Roller Flume for Computer Aided Design of MAritime Structure in 3D). At first, the accuracy of prediction of breaking point was checked in the wave flume, and the validity was verified due to comparison of the Goda's breaking index. Then, the performance of 3 dimensional breaking problems was tried. Two types of submerged breakwater were installed in our Tank. Results were qualitatively good agreement with experiments.

DOI： 10.2208/proce1989.54.71

DOI： 10.20965/jdr.2021.p1286_references_DOI_YAmwOe4EewUvHoEhMF3Bi2tFII5

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

This research investigates the protection performance against tsunami with the buoyancy- driven vertical breakwater by using the numerical simulations. Macro-Micro scale interlocked tsunami simulator named STOC (Storm surge and Tsunami simulator in Oceans and Coastal areas) has been applied to the series of simulations. Results of comparison of tsunami height in the Wakayama-shimotsu port and Fukura port due to Tokai, Tonankai and Nankai earthquakes indicates that this new breakwater decreases tsunami height and inundation area. Although the dissipating rate is depending on the position of this breakwater, the breakwater with 10% opening brings a 33% decrease in the maximum tsunami height.

DOI： 10.2208/proce1989.54.936

DOI： 10.2208/kaigan.75.i_805_references_DOI_H62efivBwebYaJ0DtM3eF8RyCh1

CiNii Research

researchmap

Language：Japanese  

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：港湾空港技術研究所  

CiNii Books

CiNii Research

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Center for Urban Earthquake Engineering  

researchmap

Language：Japanese   Publisher：国土交通省国土技術政策総合研究所  

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Society of Civil Engineers  

An innovative ‘buoyancy-driven vertical piling breakwater’ is under development to protect harbor facilities behind the breakwater against tsunamis and high waves. This breakwater consists of rows of steel pipe piles and each pile consists of upper and lower steel pipes. Upper steel pipe is normally encased in lower steel pipe which driven into seabed and thus there small gap exists between upper pipes. When tsunami or high wave is predicted, the upper pipes quickly rise up to the water surface driven by the buoyancy of air supplied into the upper pipes.<BR>A few experimental researches have been conducted on the hydraulic characteristics of this type of breakwater with gaps. In this study, hydraulic model experiments and numerical simulations were carried out to investigate the wave transmission through the breakwater and wave pressures acting on the upper pipes. As a result of the study, the breakwater's performance against tsunamis and high waves has been verified.

DOI： 10.2208/prooe.23.117

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

DOI： 10.2208/proce1989.53.796

DOI： 10.2208/kaigan.68.i_796

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

DOI： 10.2208/proce1989.52.746

DOI： 10.2208/jscejoe.69.i_407_references_DOI_DWKu9MZeQc1rqomfpd998N5NHzU

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

DOI： 10.2208/proce1989.52.46

DOI： 10.20965/jdr.2016.p0639_references_DOI_77gEj9eOvdZbqHmqsBZMdEASmGB

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

DOI： 10.2208/proce1989.52.1406

CiNii Research

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：World Scientific  

researchmap

Language：Japanese   Publisher：港湾空港技術研究所  

CiNii Books

CiNii Research

researchmap

Language：Japanese  

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

Buoyancy-driven vertical piling breakwater-a new type of breakwater formed by upper and lower steel pipes rises above sea level by feeding the air into the upper pipe when high waves or tsunamis are imminent, whereas it normally rests inside the lower pile installed below seabed so that navigation is undisturbed. This paper outlines the results of a series of experiments by a large scale physical model and of the numerical analyses with regard to the rising/sinking behavior of the breakwater. The results clearly demonstrate that: 1) The time required for raising the upper pipe is just a few minutes, being rapid enough to prevent tsunamis from attacking harbors; and 2) The numerical model gives good approximation and is fairly applicable.

DOI： 10.2208/prooe.21.115

DOI： 10.2208/jscejoe.75.i_7_references_DOI_NLnMzgMfvxT26hO9vmaJ88G4HAQ

CiNii Research

researchmap

Language：Japanese   Publisher：港湾空港技術研究所  

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：港湾荷役機械システム協会  

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：土木学会  

DOI： 10.2208/proce1989.51.866

CiNii Research

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：土木学会  

DOI： 10.2208/proce1989.51.741

CiNii Research

researchmap

Language：Japanese   Publisher：港湾空港技術研究所  

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：土木学会  

DOI： 10.2208/proce1989.50.716

CiNii Books

CiNii Research

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Society of Civil Engineers  

researchmap

researchmap

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：土木学会  

DOI： 10.2208/proce1989.49.656

CiNii Research

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：土木学会  

DOI： 10.2208/proce1989.49.26

CiNii Research

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Society of Civil Engineers  

researchmap

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：土木学会  

DOI： 10.2208/proce1989.48.101

CiNii Research

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：土木学会  

DOI： 10.2208/proce1989.48.831

CiNii Books

CiNii Research

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Society of Civil Engineers  

researchmap

Language：Japanese   Publisher：土木学会  

DOI： 10.2208/proce1989.47.186

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

DOI： 10.2208/proce1989.47.66

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

DOI： 10.2208/proce1989.46.56

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

DOI： 10.2208/proce1989.45.141

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

DOI： 10.2208/proce1989.44.91

DOI： 10.2208/jscejmcs.75.60_references_DOI_ME8j3jUv8FbmCNLA0gPhFmPFiRL

CiNii Research

researchmap

researchmap

Language：Japanese  

CiNii Books

CiNii Research

J-GLOBAL

researchmap

Language：Japanese  

CiNii Books

CiNii Research

J-GLOBAL

researchmap

Language：Japanese   Publisher：地震予知総合研究振興会  

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：土木学会  

CiNii Books

CiNii Research

researchmap

Language：Japanese  

CiNii Books

CiNii Research

researchmap

Language：Japanese   Publisher：Japan Association for Wind Engineering  

DOI： 10.5359/jawe.42.273

CiNii Books

CiNii Research

researchmap

Other Link： http://id.ndl.go.jp/bib/028439378

Language：Japanese  

CiNii Books

CiNii Research

researchmap

Language：English   Publisher：World Scientific Publishing  

researchmap