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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

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Publishing type：Research paper (scientific journal)   Publisher：International Journal of Geomate  

DOI： 10.21660/2021.81.gx172

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

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

DOI： 10.21660/2019.58.8152

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

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Language：Japanese  

DOI： 10.5030/jcigsjournal.33.27

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

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

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

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

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Korean Geosynthetics Society  

A new cost-effective high-performance bridge system, called the GRS integral bridge, was developed to alleviate several serious inherent problems with conventional type simple girder bridges: i.e., a low seismic stability of the girder and approach fills, costly massive abutments often requiring the use of pile foundation, bumps developing immediately behind the abutments, costly construction and long-term maintenance of girder bearings, etc. Both ends of the girder are structurally integrated to the top of a pair of full-height rigid (FHR) facings, while a pair of approach blocks comprising geogrid-reinforced well-compacted lightly cement-mixed well-graded gravelly soil are integrated to the FHR facings. To minimize bumps by a gradual transition from the rigid approach block to unreinforced unbound fill behind and to increase the resistance against lateral push-in loads by the seismic inertial of the girder and facings, the approach blocks are trapezoidal with the base wider than the crest. To validate this design concept, a series of shaking table tests were performed in 1g on models with a scale assumed to be 1/10 of prototype.

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

In Japan, innovations leading to lower maintenance and repair costs for asphalt pavement structures are required. For a general roadway in Japan, it is only possible to apply a soil reinforcing technology that is equivalent to excavating and backfilling concerned with maintenance of lifeline facilities. In this study, therefore, model loading tests on asphalt pavement with fiber-reinforced recycled concrete aggregate layer were performed to develop a new soil reinforcing technique that can be applied to ordinary road. As the results of the present study, it was confirmed that mixing short fiber in the subbase layer made of crushed concrete aggregate has advantage to reducing the residual settlement caused by heavy traffic load.

DOI： 10.5030/jcigsjournal.30.111

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Asian Regional Conference on Soil Mechanics and Geotechnical Engineering  

In pavement structure, short fiber reinforcing technique is hoped as an effective method for improving the stability of the subbase or subgrade layers against traffic load. In this paper, compaction behavior of short fiber reinforced is discussed by the results of laboratory compaction tests. As the results of roller compaction tests, it was confirmed that the value of σd stably increases with an increase in the number of roller passing even if initial σd value at spreading was lower. At 8 passing of roller compaction, the realized rd value around the wopt become higher than the maximum dry density (σd)max obtained from the Proctor test. This results shows that the current compaction control method for the subbase of pavement structure can also be applied to short fiber reinforced soil.

DOI： 10.3208/jgssp.JPN-080

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

J-GLOBAL

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Geosynthetics Society  

This study focused on a reinforcing method that used short fibers to reinforce the gravelly soil applied as the base course of an asphalt pavement structure. The fundamental performances of the fiber reinforced gravelly soil, such as the structure of the fiber mixed soil, compaction properties, and strength properties, were investigated using laboratory tests. The following conclusions were obtained from these experimental investigations. 1) When the fiber content of over 0.5% by dry weight of soil was used, it formed local concentrations in the soil, and the structure of the mixed soil was not uniform. 2) The compaction properties of the fiber reinforced soil were almost the same as those of the soil alone. 3) The peak strength of the gravelly soil increased when mixed with short fibers with a wide range of density condition.

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

J-GLOBAL

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPANESE GEOTECHNICAL SOC  

A comprehensive series of drained triaxial compression tests were performed on crushed concrete aggregate (CCA) moist as compacted. When compared to ordinary natural well-graded gravelly soils, the peak strength and stiffness increase more significantly with dry density, while the effect of the degree of saturation during compaction is much less significant. In a range of confining pressure of 30-600 kPa, the strength and stiffness of well-compacted CC A is similar to, or, in some cases even higher than typical selected high-class backfill materials (e.g well-graded gravelly soil of crushed quarry hard rock). The strength and stiffness of (CA with a maximum particle size D-max=37.5 mm obtained from a typical concrete crushing plant are noticeably lower than CCA sieved to D-max=19 mm compacted using the same energy. However, when compacted to the same dry density, the original (CA exhibits the strength and stiffness higher than the sieved CCA. Effects of the strength of original concrete on the strength and stiffness of compacted CCA are insignificant, while the strength and stiffness of compacted CCA are, respectively, noticeably higher than, or similar to, the original concrete aggregate (i.e., natural gravelly soil) compacted using the same energy. All these results indicate that well-compacted CCA can be used as the backfill material for important civil engineering soil structures requiring a high stability while allowing a limited amount of deformation. (C) 2013 The Japanese Geotechnical Society. Production and hosting by Elsevier B.V. All rights reserved

DOI： 10.1016/j.sandf.2013.10.003

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

A series of laboratory model tests were performed to investigate the methodology of improvement of the structural stability of embankment on slope against rainfall. In this study, the effects of geosynthetic-reinforced soil as well as drainage and filtration technologies on the stability of soil structure against rainfall were focused. As the results of experimental investigation, it was confirmed that the stability of soil structure against rainfall can be improved effectively by applying the geosynthetic-reinforced retaining wall to the toe of the embankment with drainpipes which can be maintained in working period to keep the function.

DOI： 10.5030/jcigsjournal.27.11

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Other Link： https://jlc.jst.go.jp/DN/JALC/10013790263?from=CiNii

Language：English   Publisher：Japanese Geotechnical Society  

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

To evaluate the dynamic stability of different bridge types, the results from a series of shaking-table tests on small-scale models of the following bridge types were analysed within the framework of the single-degree-of-freedom theory: (1) a conventional bridge (CB), comprising a girder (i.e. deck) supported via a pair of movable and fixed bearings (i.e. shoes) by gravity-type abutments (without a pile foundation) having unreinforced backfill; (2) a GRS-RW bridge, comprising a girder supported via a pair of movable and fixed bearings by a pair of sill beams placed on the crest of a pair of geosynthetic-reinforced soil-retaining walls (GRS-RWs) having a stage-constructed full-height rigid facing; (3) an integral bridge (IB), comprising a girder integrated to a pair of abutments (without bearings) and unreinforced backfill; (4) a GRS integral bridge, comprising a girder integrated to the abutments (in the same way as the IB bridge) while the backfill is reinforced with geosynthetic layers connected to the facings (in the same way as the GRS-RW bridge); and (5) a GRS integral bridge with a cement-mixed soil zone of rectangular prismatic or trapezoidal shape immediately behind the facing. The following is shown: the stability of the bridge against dynamic excitations increases: (1) with an increase in the initial natural frequency via an increase in the initial stiffness; (2) with a decrease in the decreasing rate of stiffness during cyclic loading (i.e. an increase in the dynamic ductility); (3) with an increase in the damping energy dissipation capacity near and at failure; and (4) with an increase in the dynamic strength. With the GRS integral bridge, the structural integration and geosynthetic-reinforcing of the backfill, as well as cement-mixing of the backfill immediately behind the facings, all contribute to the evolution of these four factors. The natural frequency can then always be kept much higher than the predominant frequency of ordinary design earthquake motion, the response acceleration is kept sufficiently low, and the dynamic stability can be kept very high.

DOI： 10.1680/gein.2012.19.1.11

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：CRC PRESS-TAYLOR & FRANCIS GROUP  

This study focuses on the residual deformation properties of the subbase of asphalt pavement subjected to traffic loading. A series of laboratory model tests was performed on asphalt pavement to investigate the effect of wheel loading on the stress conditions and deformation properties of subbase aggregates. From the results, it was confirmed that residual settlement of the subbase is affected by the following two loading conditions; a) cyclic loading from both normal and shear stresses, and b) rotation of the principal stress axes. Residual deformation of the subbase is closely related to the stability of the surface asphalt layer. Therefore, reducing aggregate movement using soil improvement technology is important for maintain the long-term stability of the pavement structure. In this study, it was confirmed that applying geogrid reinforcing technology to the subbase can effectively reduce residual settling due to wheel loading.

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

Influence of installation damage on tensile creep properties of HDPE geogrid was investigated in laboratory test. In a series of test, the temperature-acceleration creep tests were performed for geogrid which was damaged by compaction in sandwich with soil sample. New damage level evaluation method was proposed, which is based on 3D-roughness analysis and particle size of the soil sample. The proposed method is useful for evaluating influence of installation damage on tensile strength or creep property. Application of the proposed method for reliability design is also proposed.

DOI： 10.5030/jcigsjournal.26.105

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

A series of laboratory model tests on embankment were performed to investigate the method of improving the structural stability of soil structure that was constructed upon slope against rainfall. The effects of the amount of rainwater flowing into the embankment from the natural ground and the surrounding on the stability of soil structures were focused in the present study. As the results of model tests, the stability of the embankment upon slope depends on the amount of seepage pressure at toe of the slope. In the present study, it was confirmed that soil-reinforcement by using geosynthetics with counterweight for the toe and drainage is effective for improvement of structural stability of soil structure against rainfall. The geosynthetic-reinforcing is also effective against erosion due to surface water.

DOI： 10.5030/jcigsjournal.26.203

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

A simple but automated pneumatic loading system that can control the stress and strain rates for one-dimensional (1D) compression of clay was developed. The rate-dependency of stress-strain behaviour due to the viscous property of clay was investigated by 1D compression tests on standard-size specimens by various loading methods: 1) Standard Consolidation Tests (SCTs), stepwise increasing the axial stress two times every one day
2) ordinary Constant-Rateof- Strain (CRS) tests at different strain rates
3) special CRS tests including unloading and reloading cycles with different stress amplitudes at strain rates of which the absolute value was either kept constant throughout respective tests or changed at the start of reloading
and 4) special CRS tests including a number of sustained loading (SL) during otherwise primary loading or unloading or reloading at constant strain rate. Sufficiently low strain rates were employed to ensure essentially fully drained condition. The followings were found. Despite that the newly developed pneumatic loading system is rather simple, 1D compression tests following such various loading histories as above can be performed on four types of clay rather accurately. The stress-strain behaviour of clay is significantly rate-dependent, exhibiting significant creep strains at SL stages. The creep strain rate is significantly different whether SL starts during otherwise primary loading or unloading or reloading, controlled by the magnitude and sign of the initial strain rate at the start of SL. The whole observed trends of rate-dependent stress-strain behaviour can be qualitatively explained by the non-linear three-component elasto-viscoplastic model extended to cyclic loading conditions.

DOI： 10.3208/sandf.51.11

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Language：Chinese   Publishing type：Research paper (scientific journal)  

The deformation and strength characteristics of geogrid-reinforced soil retaining wall are investigated based on the results from physical model tests performed under change of loading rate. The model is vertically loaded with a rigid strip footing placed on the crest of the backfill. The vertical settlement rate of the footing is changed step by step several times and a set of creep loading and cyclic loading stages are performed during change of loading rate. The obvious rate-dependent behaviors of geogrid-reinforced soil retaining wall are observed. Namely, on a step-change in the loading rate, the footing pressure-settlement relation is changed correspondingly. It is due to the viscous properties of the backfill (sand) and the reinforcement (geogrid) and the interactions between them. On the basis of dynamic relaxation method, the nonlinear finite element method (FEM) analysis technique is developed to simulate the above physical model tests. In the FEM analyses, the unified three-component elasto-viscoplastic constitutive model is used to describe both sand and geogrid. It is shown that the aforementioned FEM can well simulate the deformation and strength behaviors of geogrid-reinforced soil retaining wall under change of loading rate.

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

Tensile strength properties of HDPE geogrid, which was damaged by compaction in sandwich with gravel, were investigated. Damage level was evaluated by surface roughness measured by a laser microscope, and deformation of tensile tests was evaluated by image analysis method. Effect of damage level on tensile strength properties is discussed statistically. Achievement of this paper will contribute for design strength evaluation of geogrid.

DOI： 10.5030/jcigsjournal.25.47

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Other Link： https://jlc.jst.go.jp/DN/JALC/00361260891?from=CiNii

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

In every year, the slope failure of embankment frequently took place in Japan. Main factors of such embankment failure are seepage flow in the embankment and surface erosion as well as lateral flow of the backfill due to saturation. It was considered that embankment stability against rainfall can be increase by draining of the porewater at the toe of slope as well as reinforcing of the backfill by using geosynthetics. In this paper, the effects of drainage of the porewater and reinforcing of the backfill with geosynthetics on embankment stability against rainfall were investigated by performing of a series of laboratory model tests. As the results of model tests, it was confirmed that drainage of the porewater and reinforcing of the backfill with geosynthetics is effective method to improvement embankment stability against rainfall.

DOI： 10.5030/jcigsjournal.25.83

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Other Link： https://jlc.jst.go.jp/DN/JALC/00361260952?from=CiNii

Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Geosynthetics Society  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Geosynthetics Society  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Geosynthetics Society  

Geogrid reinforcement technique can improve the brittle behavior of stabilized soil. This paper discusses new Finite Element (FE) analysis method to simulate mechanical behavior of reinforced-stabilized soil by geogrid. The biggest feature of the proposed analysis method is the ease of expressing discontinues deformation as separation of two adjacent Voronoi blocks owing to the particle discretization that uses nonoverlapping characteristic functions. In this paper, outline of geogrid reinforcement of stabilized soil and basic concept of new FE method are explained. Numerical simulation results for laboratory model test are shown.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：THOMAS TELFORD PUBLISHING  

Two tall geosynthetic-reinforced soil (GRS) walls, one 16.7 m high supporting a sloped embankment, and the other 21.1 m high with a level backfill, were constructed to support the taxi way of Mt. Fuji Shizuoka Airport, Shizuoka Prefecture, Japan, which was opened to service in June 2009. As only limited residual deformation during service is allowed and high stability is required, the backfill was a well-graded gravelly soil, which was well compacted at controlled water content and reinforced with geogrid reinforcement. In the respective walls, three representative geogrid layers were fitted with a number of electric-resistance strain gauges to monitor the geogrid tensile strains during and after construction to ensure high stability and sufficient serviceability. After the wall construction had been completed, the geogrid strains were either only increasing at a very low rate, or had stopped increasing, or had started decreasing. A series of in-air tensile loading tests were performed on different geogrid types used for the wall construction to evaluate their elasto-viscoplastic properties. The time histories of tensile force in the geogrid layers were estimated from the measured time histories of the geogrid strains based on a non-linear three-component rheology model using the model parameters determined by the in-air tensile loading tests. After the end of wall construction, the estimated geogrid tensile force was either increasing at a very low rate or was decreasing with time. Even at the locations where it tended to increase with time, the estimated geogrid tensile force never increased greatly by the end of a typical design life (i.e. 50 years) from the value at the end of wall construction. As the estimated maximum geogrid force at the end of the design lifetime is substantially lower than the respective design tensile rupture strengths, it is estimated that creep rupture failure of the geogrid is utterly unlikely. The analysis suggests that these estimates are also relevant when the lifetime is 100 years. The framework to estimate the time histories of reinforcement force from the time histories of measured reinforcement strains used in this study can be applied to other similar cases.

DOI： 10.1680/gein.2010.17.1.12

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Geosynthetics Society  

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

In the geosynthetics engineering field, long-term creep deformation of polymeric geogrids has been evaluated by performing of creep test under a constant temperature. However, it is difficult to directly evaluate the long-term creep deformation of polymeric geogrids corresponding to the design life time by using this method. In the present study, a series of accelerated creep tests based on time-temperature superposition principle was performed to evaluate long-term creep deformation of various types of polymeric geogrids. In total four types of geogrids made by polypropylene (PP), high-dense polyethylene (HDPE), polyester (PET) and vinylon were used. As a result of the present study, it was confirmed that accelerated creep test can evaluate the long-term creep deformation of various types of polymeric geogrids.

DOI： 10.5030/jcigsjournal.24.83

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Other Link： https://jlc.jst.go.jp/DN/JALC/00346080773?from=CiNii

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

This paper discusses on geosynthetic-erosion control method for levees. This method is an intimate river work for natural conservation. In this study, 16m-flume model tests were conducted to investigate the optimum shape of geocomposite for erosion control. This paper reports the laboratory model test results and proposed new evaluation methods for erosion control effects of geo-composite.

DOI： 10.5030/jcigsjournal.24.183

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Other Link： https://jlc.jst.go.jp/DN/JALC/00346080537?from=CiNii

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

“Geosynthetic-reinforced soil (GRS) Integral Bridge” comprises “Integral Bridge” and “Bridge with GRS Retaining Walls as Abutments”, improving the structural and soil components, respectively, of conventional type bridges. GRS Integral Bridge is characterised by; 1) the use of a continuous girder connected to the top of RC facing, without using bearings, which reduces the cost for construction and maintenance; 2) reinforcing the backfill with geosynthetic reinforcement (e.g., a geogrid) connected to the back of the facing; and 3) the staged construction of a full-height rigid facing by casting-in-place concrete on the wrapped-around wall face of the reinforced backfill after the deformation of the backfill and supporting ground by the backfill weight is over, which makes possible high compaction of the backfill immediately behind the facing and prevents the damage to the connection between the reinforcement and the facing while making the structure of the facing simple and the need for pile foundations lighter. As the facing is a continuous beam supported at many levels with a small vertical span (i.e., 30 cm), damage by annual cyclic thermal deformation of the girder and seismic load is minimised.

DOI： 10.5030/jcigsjournal.24.205

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

The geosynthetic reinforced retaining wall has been known as a highly cost-effective method for retaining wall. A new type bridge, geosynthetic-reinforced soil (GRS) integral bridge which combines integral bridge with geosynthetic reinforced backfill has been proposed. We performed a series of static loading tests and shaking table tests with small models to evaluate the stability of GRS integral bridge. The active failure and increment of earth pressure of backfill due to annual expansion and contraction of the deck is solved by geosynthetic-reinforcing of backfill. The seismic failure mechanism of GRS integral bridge is also revealed by shaking table tests. We performed another series of tests to consider the effect of structural condition to the stability of GRS integral bridge. The model test results and consideration of effect of structural condition on GRS integral bridge are summarised.

DOI： 10.5030/jcigsjournal.24.211

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Other Link： https://jlc.jst.go.jp/DN/JALC/00346080582?from=CiNii

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：International Society for Soil Mechanics and Geotechnical Engineering  

Drained constant-rate-of-strain one-dimensional compression tests at different strain rates with and without large unload/reload cycles and many sustained loading (SL) stages, as well as standard consolidation tests, were performed on reconstituted and undisturbed soft clays. Significantly rate-dependent stress-strain behaviour of Isotach type, not due to delayed dissipation of excessive pore water pressure but due to the viscous properties of clay, was observed. The creep axial strain rate at SL stages while otherwise the effective axial stress σ′ a was increasing at positive axial strain rates ε̇ a was always positive. The creep axial strain rate at SL stages while otherwise σ′ a was decreasing was basically negative, whereas it was positive immediately after load reversal from primary loading. Irrespective of the signs of current σ̇′ a and ε̇ a, primary loading and reloading are defined by ε̇ a ir &gt
0, while unloading by ε̇ a ir &lt
0. These trends of behaviour are simulated by the non-linear three-component elasto-viscoplastic model. © 2009 IOS Press.

DOI： 10.3233/978-1-60750-031-5-303

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

Geosynthetic-Reinforced Soil Integral Bridge (GRS-IB) consists of an integral bridge comprising a girder unified to a pair of abutment and the backfill reinforced with geosynthetic-reinforcement layers connected to the back of the facing. It is shown that, cement-mixing the backfill zone immediately behind the abutment, GRS-IB becomes more stable against seismic load as well as cyclic displacements at the top of the abutment due to seasonal thermal deformation of the girder. Failure of GRS-IB is triggered by passive failure at the top of backfill, which results into a pushing out of the bottom of the abutment. It is effective for an increase in the stability of GRS-IB against both seismic and static loading to increase the passive resistance by cement-mixing a relevant zone of the backfill. The above was validated by performing a series of shaking table tests and static cyclic lateral loading tests on scaled models of GRS-IB.

DOI： 10.5030/jcigsjournal.23.161

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Other Link： https://jlc.jst.go.jp/DN/JALC/00322671636?from=CiNii

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

The effects of pile foundation on the stability of GRS integral bridge were investigated by performing the followings two model loading tests; a) lateral loading model wall tests that was simulated to the thermal lateral cyclic displacements at the top of the facing caused by seasonal thermal expansion and contraction of the bridge girder, and b) 1g shaking table tests. From the results of the lateral loading wall tests, the residual settlement of backfill due to the thermal cyclic displacement of the girder were fully alleviated by not only reinforcing the backfill but also fixing the lateral displacement of bottom of the facing by using of pile foundations. On the other hand, it was confirmed that the seismic stability of GRS integral bridge without pile foundation is sufficiently high. The seismic stability of GRS integral bridge does not increase when pile group with short piles were applied. It is necessary to apply group pile with short piles to ensure sufficiently high stability of GRS integral bridge.

DOI： 10.5030/jcigsjournal.23.169

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Other Link： https://jlc.jst.go.jp/DN/JALC/00322671643?from=CiNii

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：地盤工学会  

A series of falling weight deflectmeter tests (FWD tests) and plate loading tests (PLT) were performed in the laboratory to evaluate the stiffness of sand ground and to compare the responses from these two types of loading tests. The plate diameters were 150 and 300 mm for both types of tests. The model ground was made of air-dried poorly graded angular silica sand. The ground stiffness from the FWD tests was larger than the one from the PLT under otherwise the same conditions. It was found that this difference is caused by the fact the plate settlement velocity in the FWD tests is substantially higher, by a factor of about 104, then that of the PLT and due mainly to the following two factors: a) the loading rate effects by material viscosity of the backfill soil; and b) effects of dynamic response of the ground in the FWD tests. The methods to correct FWD test results for these two factors were developed and proposed. The relationships between the plate pressure and the settlement from the FWD tests corrected for these two factors agree rather well with those from the PLT. It is shown that the ground response in FWD tests becomes closer to that in PLT by decreasing the stiffness of the buffer used in the FWD tests. A method to infer the plate pressure - settlement relation under the PLT loading conditions from FWD tests using buffers having different stiffness values is suggested.

DOI： 10.3208/jgs.3.307

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

Authors examine reinforcing effect of stabilized soil. Two kinds of consolidation conditions were compared based on the idea that curing and consolidation are advancing simultaneously in the reinforced-stabilized ground. Compared one is a case where an underwater curing period is long and consolidation time is short, the other is a case where an underwater curing period is short and consolidation time is long. Reinforcing effect was evaluated as apparent cohesion regardless of consolidation condition. In a case where underwater curing period is short and consolidation time is long, the higher strength was observed.

DOI： 10.5030/jcigsjournal.23.59

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Other Link： https://jlc.jst.go.jp/DN/JALC/00322671865?from=CiNii

Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Geosynthetics Society  

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

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

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japanese Geotechnical Society  

A series of plane strain compression (PSC) tests were performed on large sand specimens unreinforced or reinforced with prototype geosynthetic reinforcements, either of two geogrid types and one geocomposite type. Local tensile strains in the reinforcement were measured by using two types of strain gauges. Sustained loading (SL) under fixed boundary stress conditions and cyclic loading (CL) tests were performed during otherwise monotonic loading at a constant strain rate to evaluate the development of creep deformation by SL and residual deformation by CL of geosynthetic-reinforced sand and also residual strains in the reinforcement by these loading histories. It is shown that the creep deformation of geosynthetic-reinforced sand develops due to the viscous properties of both sand and geosynthetic reinforcement, while the residual deformation of geosynthetic-reinforced sand during CL (defined at the peak stress state during CL) consists of two components: i) the one by the viscous properties of sand and reinforcement
and ii) the other by rate-independent cyclic loading effects with sand. The development of residual deformation of geosynthetic-reinforced sand by SL and CL histories had no negative effects on the subsequent stress-strain behaviour and the compressive strength was maintained as the original value or even became larger by such SL and CL histories. The local tensile strains in the geosynthetic reinforcement arranged in the sand specimen subjected to SL decreased noticeably with time, due mainly to lateral compressive creep strains in sand during SL of geosynthetic- reinforced sand. This result indicates that, with geosynthetic-reinforced soil structures designed to have a sufficiently high safety factor under static loading conditions because of seismic design, it is overly conservative to assume that the tensile load in the geosynthetic reinforcement is maintained constant for long life time. Moreover, during CL of geosynthetic-reinforced sand, the residual tensile strains in the geosynthetic reinforcement did not increase like global strains in the geosynthetic-reinforced sand that increased significantly during CL. These different trends of behaviour were also due to the creep compressive strains in the lateral direction of sand that developed during CL of geosynthetic-reinforced sand. Copyright© 2005-2009 National Institute of Informatics.

DOI： 10.3208/sandf.48.333

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：TAYLOR & FRANCIS LTD  

Modified Bishop's and Fellenius' slice methods were used in the stability analysis of the behaviour of a set of unreinfored and nailed model sand slopes in loading tests in the laboratory. One of the Bishop's methods (i.e., method 4) successfully simulates the ultimate footing load and the location of slip surfaces for the unreinforced slope and most of the reinforced slopes reinforced slope with various types of facing. This method takes into account the soil strength increase induced by the reinforcement force. An exceptional case in which the experimental and the analytical results are inconsistent as observed in Test No. I on a reinforced slope is explained by the so-called 'wide-slab' effect that was not taken into account in this analysis.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：TAYLOR & FRANCIS LTD  

A series of loading tests on nailed model sand slope covered with various types of facing was performed to investigate the effect of facing rigidity on the load-settlement behavior of nailed slopes loaded on its crest. The test results showed that the ultimate bearing capacity (i.e., the stability) of the nailed slope was effectively increased with an increase in the facing rigidity by using continuous stiff and/or flexible panel facings. It was also shown that the post-yielding strain hardening behavior of the nailed slope becomes significantly ductile by using effectively facing having a relevant rigidity.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：TAYLOR & FRANCIS LTD  

A new type bridge combining an integral bridge and a pair of geosynthetic-reinforced soil (GRS) retaining walls having full-height rigid (FHR) facings, called the GRS integral bridge, is proposed. The geosynthetic reinforcement layers are connected to the facings (i.e., RC parapets) that are integrated with a girder. The GRS integral bridge is much more cost-effective in construction and long-term maintenance while having a higher seismic stability than conventional-type bridges having a girder via movable and fixed supports on either gravity-type abutments or GRS retaining walls and also than the conventional integral bridges. The GRS integral bridge alleviates several problems with the other types, mostly resulting from that the backfill is not reinforced and girder-supports are used, while taking advantage of their superior features.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：TAYLOR & FRANCIS LTD  

A new bridge system comprising of a pair of geosynthetic-reinforced soil (GRS) retaining walls having full-height rigid facings unified with a girder is proposed. Shaking table tests were performed on five GRS integral bridge models to evaluate the effect of the tensile resistance of reinforcement layers on the seismic stability of the bridge. The dynamic stability of integral bridge increases by reinforcing the backfill and by increasing the tensile resistance of reinforcement layers, which increases with an increase in the number of reinforcement layer as well as an increase in the connection strength between the facing and the reinforcement layer for give pull-out strength and tensile rupture strength of reinforcement.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：TAYLOR & FRANCIS LTD  

Shaking table tests were performed on scaled models of four different bridge types: 1) the conventional-type, comprising of a pair of gravity-type abutments retaining unreinforced backfill; 2) the GRS RW bridge, comprising of a pair of geosynthetic-reinforced soil (GRS) retaining walls with full-height rigid (FHR) facings directly supporting a girder on the crest of the reinforced backfill; 3) the conventional integral bridge with unreinforced backfill, unifying a pair of FHR facings with a girder; and 4) a new type integral bridge comprising of a pair of GRS retaining walls having FHR facings (called the GRS integral bridge). It is shown that the seismic stability of the GRS integral bridge is highest among the four types examined because of several inherent structural advantages resulting in a monolithic behaviour of the whole bridge system.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ZHEJIANG UNIV PRESS  

To confirm a very low possibility of tensile rupture until the end of specified life time of polymer geogrids arranged in a full-scale reinforced soil retaining wall (21 m-high with a slope of 1:0.3 in V:H) constructed to support a taxi way of an airport, time histories of tensile force in the reinforcement were estimated based on those of measured tensile strain in the reinforcements in the wall. To this end, tensile tests were performed on the geogrids and their elasto-viscoplastic properties were evaluated. A constitutive model was developed based on the test results. The model was validated by that the model can accurately predict the tensile load-strain-time behaviour of the geogrids when subjected to arbitrary loading histories. The time histories of tensile force in the geogrids in the wall estimated from the measured tensile strains based on the model indicate that, even in the most severe case among those analysed, the tensile force will increase with time to a very limited extent, towards a value significantly lower than the tensile rupture strength at the end of life time. This result indicates that eventual creep rupture of the geogrids in the wall is not likely unless significant degradation takes place.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ZHEJIANG UNIV PRESS  

A new bridge system, called the GRS integral bridge, is proposed. This consists of an integral bridge, which integrates a pair of RC abutment and a continuous girder without using girder supports, and a pair of geosynthetic-reinforced soil (GRS) retaining walls having full-height rigid (FHR) facings constructed after the completion of reinforced backfill walls. A pair of FHR facing function as the abutments to which a girder is integrated. Results from model tests indicate that, when reinforcement layers are firmly connected to the FHR facing, GRS integral bridges become much more cost-effective in construction, long-term maintenance and stability than conventional type bridges, integral bridges with unreinforced backfill and bridges using GRS retaining walls as abutments.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japanese Geotechnical Society  

The viscous properties of a variety of poorly graded unbound granular materials were investigated by direct shear tests on 12 cm-cubic specimens. A number of natural sands having different particle shapes and sizes as well as uniform glass beads having different particle sizes were used. The viscous properties were evaluated by changing the shear displacement rate many times during otherwise monotonic loading (ML) at constant shear displacement rate and normal pressure. Creep loadings were performed in two tests. Different types of viscous properties, which are affected by the particle shape but essentially independent of the particle size, are reported. The viscosity type varies as the shear displacement increases from the pre-peak regime towards the residual state. A new viscosity type, called "Positive &amp
Negative", was found with relatively round granular materials in the pre-peak regime and with relatively angular granular materials in the post-peak softening regime and at the residual state. Peculiar "rate-independent unstable behaviour" is observed with round natural sands and glass beads in the post-peak regime, which is more significant and frequent with glass beads. Controlled by the particle size, this behaviour is caused by the so-called stick/slip phenomenon. The viscous properties observed in the DS tests are quantified by the rate-sensitivity coefficient denned in terms of the shear and normal stresses, which are then converted to those defined in terms of the major and minor principal stresses, β13. These β13 values are consistent with those directly obtained by the triaxial and plane strain compression tests. The effects of particle size on the β13. value are negligible and the β13. value tends to decrease as the particle shape becomes more round.Copyright© 2005-2009 National Institute of Informatics.

DOI： 10.3208/sandf.48.297

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IOS PRESS  

The viscous property of an air-dried poorly graded sub-angular to angular quartz-rich fine sand (Toyoura sand) was evaluated by using an advanced direct shear (DS) apparatus. A series of monotonic loading (ML) tests were performed at a constant normal pressure and at constant shear displacement rates different by a factor of up to 100,000. A set of ML tests including stepwise changes in the shear displacement rate, (s) over dot, were also conducted. With dense specimens, the viscous property changes with an increase in the shear displacement from "so-called TESRA" in the pre-peak regime toward "so-called Positive & Negative" in the post-peak regime. In ML at a constant (s) over dot, the peak shear strength is independent of (s) over dot, while the residual shear strength decreases with an increase in (s) over dot, With loose specimens, the transition of viscosity type starts before the peak stress state. Both peak and residual shear strengths in ML at a constant (s) over dot, with an increase in (s) over dot, more noticeably with the residual shear strength. The viscous property was quantified in terms of the rate-sensitivity coefficients.

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

An integral bridge, unifying a pair of RC facing and a continuous girder with unreinforced backfill, is known to cost-effective in construction and long-term maintenance. However, cyclic lateral displacements at the top of the facing caused by seasonal thermal expansion and contraction of the girder gradually increase settlements in the backfill and the earth pressure on the back of the facing, which may damage the facing and the head of piles if used and/or the facing bottoms are pushed out. As a new bridge type alleviating these problems, the GRS integral bridge, which combines an integral bridge and a pair of geosynthetic-reinforced soil (GRS) retaining walls having full-height rigid (FHR) facings, is proposed. To evaluate the performance of the conventional and new types of integral bridge, model tests were performed. Cyclic lateral displacements were applied at the top of the facing. The backfill was either unreinforced or reinforced with the reinforcement connected, or not connected, to the facing. The facing bottom was either hinge-supported allowing only rotation or not supported with a foundation with a small depth in the subsoil. When the backfill was not reinforced, large settlements in the backfill and a large earth pressure increase associated with a significant active failure in the backfill were observed. When the reinforcement was not connected to the facing, reinforcing the backfill did not alleviate these problems. These problems were fully alleviated when the reinforcement was connected to the facing even in the case where the facing bottom was not supported with a foundation.

DOI： 10.5030/jcigsjournal.22.77

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Other Link： https://jlc.jst.go.jp/DN/JALC/00311684258?from=CiNii

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

DOI： 10.5030/jcigsjournal.21.159

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Society for Soil Mechanics and Geotechnical Engineering  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Society for Soil Mechanics and Geotechnical Engineering  

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

To investigate the deformation and strength characteristics of EPS-beads mixed sand, multiple series of laboratory triaxial compression tests were conducted under various values of the volume ratios of Toyoura sandand EPS-beads. In one of the test series, cement was not added, while in the other test series, cement was added.The small-strain properties of Young's modulus and Poisson's ratio were examined in detail under various stress conditions.

DOI： 10.5030/jcigsjournal.22.41

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Other Link： https://jlc.jst.go.jp/DN/JALC/00311684203?from=CiNii

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

The viscous property of polymer geosynthetic reinforcement, which causes creep deformation, is first summarised. The creep deformation and associated creep rupture characteristics, when subjected to long-term sustained loading under the following three conditions, are numerically simulated based on a non-linear three-component rheology model: (a) the load strain behaviour is always free from material degradation; (b) the load-strain behaviour exhibits simultaneous viscous effects and material degradation as in usual actual field cases; and (c) the sustained loading starts after full material degradation has taken place. Case (c) is the one assumed in the currently most popular design method, in which the long-term tensile design strength is obtained by separately applying reduction factors for creep rupture and material degradation. This method underestimates the true creep rupture strength to an extent that depends on the viscous and material degradation properties of the geosynthetic reinforcement. In this paper a new method to obtain the design tensile strength is proposed, taking into account the new creep-rupture curve for simultaneous creep deformation and degradation.

DOI： 10.1680/gein.2007.14.4.189

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Society for Soil Mechanics and Geotechnical Engineering  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPANESE GEOTECHNICAL SOC  

A number of previous experimental studies showed that polymer geogrid reinforcement as well as sand exhibit significantly rate-dependent behaviour. The viscous properties of polymer geogrids and Toyoura sand were independently evaluated by changing stepwise the strain rate as well as performing sustained loading and load/stress relaxation tests during otherwise monotonic loading in, respectively, tensile loading tests and drained plane strain compression (PSC) tests. The viscous properties of the two types of material were separately formulated in the same framework of non-linear three-component rheology model. The viscous response of geogrid-reinforced sand in PSC is significant, controlled by viscous properties of geogrid and sand. Local strain distributions in the reinforced sand specimen were evaluated by photogrametric analysis and used to determine the time history of the tensile strain in the geogrid. The time history of tensile load activated in the geogrid during sustained loading of reinforced sand specimen was deduced by analysing the measured time history of geogrid strain by the non-linear three-component model. It was found that the tensile load in the geogrid reinforcement arranged in a sand specimen subjected to fixed boundary loads could decrease with time. In that case, the possibility of creep rupture of geogrid is very low.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPANESE GEOTECHNICAL SOC  

To evaluate the effects of reinforcement type in terms of stiffness, viscous property, rupture strength, shape and loading history on the stress-strain behaviour during primary, sustained and cyclic loading of reinforced sand, a series of drained plane strain compression tests were performed on Toyoura sand. The sand specimens were reinforced with two types of polymer geogrid as well as two types of metal grid, having largely different stiffness values and surface conditions. Despite that the effects of reinforcement type on the overall stress-strain characteristics of reinforced sand and their rate-dependency are significant during primary loading, the effects are much smaller than the difference in the stiffness of reinforcement. The effects of reinforcement type on the global unloading behaviour and the residual strain by cyclic loading during otherwise global unloading are generally insignificant or negligible. The residual strains by cyclic loading of reinforced sand became substantially small by preloading as well as pre-sustained loading and precyclic loading at higher load levels. With this procedure, polymer geosynthetic reinforcement, which is much more extensible and viscous than metal reinforcement, can be used to reinforce soil structures allowing very limited residual deformation.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPANESE GEOTECHNICAL SOC  

The viscous properties of three types of geogrid polymer were evaluated by sustained loading tests lasting for 30 days at a load level about a half of its nominal rupture strength. The sustained loading tests were performed during otherwise monotonic loading (ML) at constant strain or load rate, unlike the conventional creep tests, in which the strain rate immediately before the start of sustained loading, which controls the creep strain rate, is not controlled or even not recorded. The following are presented in this study. The tensile rupture strength measured by ML that was started following a 30 day-long sustained loading was essentially the same as the one at the same strain rate at rupture obtained by continuous ML without any intermission of sustained loading. This fact indicates that creep is not a degrading phenomenon. Then, if free from chemical and mechanical degrading effects, the strength of a geosynthetic reinforcement (for a given strain rate at rupture) can be maintained until late in its service life. A non-linear three-component model is used to simulate the experimental results from the previous and present studies. The model can simulate very well not only the load-strain behaviour during ML with and without step changes in the strain rate and the one after sustained loading, but also the time histories of creep strain during sustained loading for short (one hour) and long (30 days) periods.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japanese Geotechnical Society  

The effects of geosynthetic reinforcement type on the strength and stiffness of reinforced sand were evaluated by per-forming a series of drained plane strain compression tests on large sand specimens. The reinforcement type is described in terms of the degree of unification of the constituting components (for geocomposites) as well as the tensile strength and stiffness, the covering ratio and others (for geocomposites and geogrids). Sand specimens reinforced with different geosynthetic reinforcement types exhibited significantly different reinforcing effects. A geocomposite made of a woven geotextile sheet sandwiched firmly with two sheets of non-woven geotextile, having a 100% effective covering ratio, ex-hibited reinforcing effects higher than typical stiff and strong geogrids. With some geocomposite types, the reinforcing effects increase substantially by better unifying longitudinally arranged stiff and strong yarns and non-woven geotextile sheets. When fixed firm to the yarns, the non-woven geotextile sheets function like the transversal members of a ge-ogrid by locally transmitting load activated by interaction with the backfill to the yarns. These geocomposites can ex-hibit reinforcing effects equivalent to those with stiff and strong geogrids. Local strain fields of the specimens are presented to show that, for reinforced sand, the peak stress state reached is always associated with the development of shear band(s) in the sand and a higher peak strength is achieved when the strain localisation starts at a larger global axi-al strain due to better reinforcing effects.

DOI： 10.3208/sandf.47.1109

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPRINGER  

Permeation grouting has been developed as one of countermeasures against soil liquefaction during earthquakes. This study aims at examining the small strain properties and cyclic resistance of jellied sand improved by silicate-based permeation grouting. In the first part of the present study, the small strain properties and cyclic resistance of jellied sand were examined based on the measurements of propagation velocities of longitudinal and shear waves travelling through triaxial specimens and the results from subsequently conducted undrained cyclic triaxial tests. In the second part, strain-controlled small-amplitude cyclic triaxial tests are conducted using non-contact gap displacement transducers to examine the initial elastic moduli of silicate gel itself and intact sand as well as jellied sand. The roles of the stiffness at small and large strains of silicate gel in increasing the undrained cyclic resistance of jellied sand are discussed in detail.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPRINGER  

A pair of about 11 m-high soil retaining walls of an U-shaped underground reinforced concrete (RC) structure in Tokyo exhibited a large residual inward (i.e., toward the active side) displacement with potential structural damage, which became 18 cm between the tops of the two walls about three years after its completion. Noticeable settlements of the backfill were observed behind the walls. A series of small-scale model tests was performed in the laboratory to understand this field behaviour. The results from in-situ investigation and model tests showed that this wall behaviour can be attributed to a gradual increase in the residual lateral earth pressure, resulting from cyclic lateral displacements of the walls caused by a small number of relatively large seasonal thermal cyclic displacement of the RC wall facing and bottom slab of the structure, not by a great number of relatively small daily displacement. Three factors for the mechanism of this wall behaviour (i.e., ratcheting, cyclic hardening and cyclic loading-induced residual deformation of the backfill) were identified and analyzed based the model test results. The settlement in the backfill observed in the model tests is consistent with the field behaviour.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

A series of large-size plane strain compression (L-PSC) tests were performed on dense air-dried Toyoura sand reinforced by six layers of: a) two types (stronger and weaker) of geocomposite (GC); and b) one type of woven geotextile sandwiched by two non-woven sheets (SW-GT). The GCs basically consist of yarns for a reinforcing function and a non-woven geotextile (N-GT) sheet for drainage and/or separation functions. The two GC types have similar shapes of tensile load-strain relation whereas the ultimate strength and stiffness are largely different. On the other hand, the rupture strength of SW-GT is about 75% of the average of the values of the two types of GCs. In this study, the degree of unification between the yarns and the N-GT sheet of the weaker type of GC was improved by the following two treating methods: a) the yarns were very partially fixed to the N-GT sheet (lightly treated); and b) the full-length (23cm) of the yarns was fixed by gluing to the N-GT sheet (fully treated). The compressive strength of reinforced sand in L-PSC drastically increased when compared to the unreinforced sand and the strength increase was particularly large when the GC was fully treated. When fully treated, the tensile force mobilised in the N-GT sheet is fully transferred to the yarns, allowing the GC to effectively work as reinforcement having a mobilised covering ratio (CR) of 100%. When not treated, the mobilised CR of the GC reduced to a lower value. The sand specimen reinforced with the SW-GT, having an effective value of CR equal to 100% because of a nearly perfect fixation between the woven and non-woven sheets, showed the highest compressive strength, despite that the strength of the SW-GT was noticeably smaller than that of the untreated stronger type of GC. These tests results indicate that sufficient unification between the yarns and the N-GT for a GC is very important for the GC to effectively function as reinforcement at least in the scale of the present PSC tests. Further study will be necessary to examine whether this conclusion derived from laboratory test results can be applied to full-scale field cases.

DOI： 10.5030/jcigsjournal.21.333

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

DOI： 10.5030/jcigsjournal.21.167

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

DOI： 10.5030/jcigsjournal.21.175

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Geosynthetics Society  

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：MILLPRESS SCIENCE PUBLISHERS  

Forced cyclic lateral displacements took place at the wall by thermal expansion/contraction of RC facing of a 11 m-high U-shape soil retaining wall due to daily and seasonal changes of the temperature, which resulted into large residual lateral displacements toward the active side of the wall due to the increment in the residual earth pressure as well as large settlement in the backfill behind the wall facing. A set of small-scale model tests was performed in the laboratory. It was found that these detrimental effects can be removed by reinforcing the backfill with polymer geogrid layers that are connected to the back face of thin RC facing.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：MILLPRESS SCIENCE PUBLISHERS  

Not only geomaterial (i.e., clay, sand, gravel and soft rock) but also polymer geosynthetic reinforcement are known to exhibit more-or-less rate-dependent stress-strain or load-strain behaviour due to their viscous properties. Due to interactions between the elasto-viscoplastic properties of backfill and reinforcement, the rate-dependent deformation of backfill reinforced with polymer geosynthetic reinforcement becomes highly complicated. In the present study, incorporating elasto-viscoplasticity constitutive models of both sand and geogrid, plane strain FE analysis of the behaviour of a geosynthetic-reinforced soil retaining wall model vertically loaded with a rough rigid, footing on the crest was performed.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

The Time-Temperature Superposition (TTS) and Stepped Isothermal Method (SIM) have been implemented to accelerate the creep deformation rate in the tensile creep tests of geosynthetic reinforcement by, respectively, performing a set of tests at different elevated ambient temperatures or stepwise increasing the temperature during sustained loading in a test using a single specimen. Creep strain rates at a fixed reference temperature are estimated by extrapolating those observed at elevated temperatures toward longer elapsed time based on several assumptions validated by a limited amount of experimental data. Any relevant constitutive model that is able to simulate in a systematic way the temperature effects on the load-strain behaviour as observed in the TTS and SIM tests has not been proposed. The stress-strain curves in TTS and SIM tests as well as those from continuous monotonic loading tests at elevated constant temperature are simulated by a constitutive model that takes into account the temperature effects as well as the viscous property. Effects of an increase in the ambient temperature from the reference value to a higher value are modelled by decreasing the stiffness as a result of negative temperature effects on the plastic property (equivalent to negative ageing effects). It is assumed that the elastic and viscous properties are not affected by temperature changes. It is shown that the time history of creep strain and the acceleration of creep strain rate upon an increase in the temperature in TTS and SIM tests can be simulated very well by the proposed model.

DOI： 10.5030/jcigsjournal.20.263

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

DOI： 10.5030/jcigsjournal.20.229

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

DOI： 10.5030/jcigsjournal.20.235

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：MILLPRESS SCIENCE PUBLISHERS  

A series of laboratory model tests of a surface strip footing on air-dried sand was performed to evaluate the effects of the material viscosity of sand on the residual displacement characteristics of footing. The viscous deformation properties in the model tests were quantified in the framework of a non-linear three-component theology model and compared with those from laboratory stress-strain tests. The following conclusions can be derived from the test results in this study; I) significant effects of the material viscosity of the sand were observed on the footing pressure and footing settlement relation when the footing settlement rate was changed stepwise and sustained loading and load-relaxation tests were performed during otherwise monotonic loading tests on a model footing on air-dried sand. 2) the material viscous property of the model ground was quantified in terms of the rate- sensitivity coefficient, 8, defined in the framework of a non-linear three-component model not as the Newtonian viscosity.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

A number of previous experimental studies showed that polymer geogrid alone as well as sand alone exhibit significantly viscous behaviour. It is shown that the viscous response of geogrid-reinforced sand is also significant due to the viscous properties of both geogrid and sand. Due to their extremely complicated interaction, the investigation of this issue only by experimental study is insufficient. A non-linear three-component model that is known to be able to simulate very well the viscous behaviour of soil was implemented into a non-linear elasto-plastic FE code. The viscous behaviour of geogrid observed in tensile tests and that of sand and geogrid-reinforced sand observed in plane strain compression tests were successfully simulated by the FEM analysis. The FEM analysis showed that the tensile force of geogrid during sustained loading of reinforced sand decreases with time.

DOI： 10.5030/jcigsjournal.19.237

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

DOI： 10.5030/jcigsjournal.19.211

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Geosynthetics Society  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Geosynthetics Society  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Geosynthetics Society  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Geosynthetics Society  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Geosynthetics Society  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Geosynthetics Society  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：THOMAS TELFORD PUBLISHING  

To evaluate the deformation characteristics of geosynthetic reinforcement under cyclic loading conditions, a series of tensile loading tests were performed on three types of polymer geogrid and one type of geocomposite using a wide variety of loading histories, including cyclic loading and sustained loading applied during otherwise monotonic loading. In order to separate the loading rate effects due to viscous properties from the rate-independent cyclic loading effects, cyclic loading was applied at five different frequencies for the same total period of cyclic loading at several base loads using two different load amplitudes. It is shown that the residual strain that develops during a given cyclic loading history is controlled essentially by the total period of cyclic loading, whereas it is independent of loading frequency (i.e. independent of the number of loading cycles). That is, the residual strain that develops during a given cyclic loading history is due mostly to the intrinsic viscous properties of the respective geosynthetic reinforcement type. The whole relationship between the tensile load and the tensile strain measured from the start to the end of the respective test, which consisted of monotonic loading and cyclic or sustained loading or both, was successfully simulated by a non-linear three-component theology model with parameters that do not incorporate any rate-independent cyclic loading effects.

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Publisher：The Japanese Geotechnical Society  

DOI： 10.11512/jiban.JGS39.0.683.0

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

In the design procedure of geosynthetic reinforced-soil structures, the residual deformation during the service period of the structure is one of the key issues. To investigate the development of residual strain of polymer reinforcements, a series of load-controlled tensile tests was performed generating the following loading histories: a) continuous monotonic loading (ML) at a constant load rate; b) creep (or sustained) loading; and c) cyclic loading with controlled amplitudes and frequencies. Though it has been usually considered that residual straining during cyclic loading is due to the effects of time-independent cyclic loading history (i. e., as a function of the number of loading cycles; amplitude; and so on), it was found from this study that cyclic residual straining is due essentially to the loading rate effects caused by material viscous property. A non-linear three-component model originally developed for simulating the rate-dependent deformation of geomaterials (i. e., soils; and rocks) was modified to simulate the relationship between tensile load and strain for ML; creep; cyclic loading; and general loading histories obtained from the present study.

DOI： 10.5030/jcigsjournal.18.183

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

DOI： 10.5030/jcigsjournal.18.167

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

DOI： 10.5030/jcigsjournal.18.175

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Geosynthetics Society  

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：A A BALKEMA PUBLISHERS  

To predict the long-term residual deformation of reinforced soil structure by sustained load and cyclic loading such as traffic loading, a series of laboratory model tests were performed on reinforced soil structure models. Creep and cyclic vertical loading were performed during otherwise primary loading, at the maximum load (i.e., preloaded) state and at unloaded prestressed states. The strain rate was changed stepwise during otherwise monotonic loading. Noticeable loading rate effects due to the material viscous property were observed during primary loading and preloading states, which decreased substantially by largely unloading to prestress states. Residual deformation taking place during cyclic loading with relatively small stress amplitude was mostly due to the viscous property, while the effects of cyclic loading increased with the cyclic stress amplitude. The model result was simulated by a non-linear three-component model based on the viscous property formulated based on the observed viscous property.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：THOMAS TELFORD PUBLISHING  

A series of conventional and unconventional tensile tests were performed on six types of geosynthetic reinforcement to evaluate their viscous properties. It is shown that the isochronous model, according to which the load (or the stress) is a unique function of instantaneous strain and elapsed time, is unable to explain the major viscous aspects of the test results. In particular the model is unable to predict the stress-strain behaviour and rupture strength observed after loading is restarted at a constant strain rate following a creep loading or stress relaxation stage. It is argued that the widely prevailing concept that creep is a degrading phenomenon requiring the design strength to be reduced with an increase in the design lifetime is not realistic under typical field conditions where the stress-strain property does not deteriorate noticeably with time. It is also argued that this concept stems from the isochronous model. A non-linear three-component model is proposed to simulate the viscous aspects of the strength and deformation characteristics of the tested geosynthetic reinforcements. It is shown that this rheology model can simulate very well the experimental results obtained by the present study.

Web of Science

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Publisher：The Japanese Geotechnical Society  

DOI： 10.11512/jiban.JGS38.0.1771.0

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Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.5030/jcigsjournal.17.221

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

DOI： 10.5030/jcigsjournal.17.129

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

Residual deformation of two types of geogrid subjected to cyclic loading, simulating traffic loading, was evaluated by performing a series of load-controlled cyclic loading tensile tests. Cyclic tensile loads were applied at two or three different load levels, at five different loading frequencies with two different load amplitudes. Creep loading tests were performed at the same loading levels as the cyclic loading tests. The two potential influencing factors for the development of residual deformation of geogrid during cyclic loading are; 1) loading rate effects due to material viscous properties; and 2) time-independent cyclic loading effects. Among the two, the loading rate effects are much more dominant on the residual deformation during cyclic loading within the limit of the test conditions in the present study, showing that it is necessary to introduce the loading rate effects in a constitutive model to predict the residual deformation of geogrid subjected to cyclic loading.

DOI： 10.5030/jcigsjournal.17.159

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

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Geosynthetics Society  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Society for Soil Mechanics and Geotechnical Engineering  

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

To evaluate the effects of preloading and prestressing on deformation characteristics by cyclic loading for a long term performance of reinforced soil structures, a series of cyclic and creep tests were performed on small models. No distinct difference was found in the increasing rate with time of residual strain between a cyclic loading test and a constant pressure creep test at a preloading state. The amount of residual strain by cyclic loading at an unloaded state (i. e., prestressed state) decreased by applying in advance long-term constant pressure or cyclic loading at the preloaded condition. Applying cyclic loading at the preloading state was slightly more effective. When swelling was allowed to take place at a prestress state. the deformation during the subsequent cyclic loading test became larger.

DOI： 10.5030/jcigsjournal.16.155

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

The isochronous theory is popular in modelling the time-dependant strength and deformation characteristics of polymer geotextile for the design of reinforced soil structures. According to this theory, the tensile load of reinforcement is a function of instantaneous strain and elapsed time. Thus, the design strength would reduce monotonously with time elapsing. It is shown that the isochronous concept is not able to explain the tensile behavior of reinforcement observed in the present study, in particular the behavior after loading is restarted at a constant strain rate after a creep and relaxation. Experimentally observed time dependency of tensile characteristics of geogrid is reported, and an analytical simulation of the tension test results on geogrid by one type of three-component model was performed. The results of an experimental and analytical investigation showed that the proposed constitutive model is relevant to simulate the time-dependent deformation and strength characteristics of the tested geogrid.

DOI： 10.5030/jcigsjournal.16.19

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：International Society for Soil Mechanics and Geotechnical Engineering  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japanese Geotechnical Society  

Plane strain compression tests were performed on large specimens that were either unreinforced or reinforced with 6 or 11 layers of geogrid, both 57.0 cm in height and 24.4 cm × 21.4 cm in cross-section. It is shown that the effects of covering ratio for each grid layer is much more important than the total tensile stiffness of grid within the limits of the test conditions in this study. Numerical analysis of the test results by a plane strain non-linear elasto-plastic FEM was performed considering strain localisation as well as anisotropic stress-strain behaviour of sand and interface properties. The geogrid was modelled as a planar reinforcement. Not only the pre-peak stress-strain behaviour of the unreinforced and reinforced specimens, but also the peak strength, post-peak behaviour and dilatancy characteristics from the FEM analysis all compared well with those from the physical tests. The effects of reinforcement rigidity and covering ratio were also well simulated. The relationship between the reinforcement covering ratio in the physical tests and the equivalent interface friction angle for the FEM analysis that provides the same reinforcing effects is presented. The mechanism of tensile-reinforcing is analysed based on local stress paths within the reinforced sand obtained from the FEM analysis.

DOI： 10.3208/sandf.40.3_55

Scopus

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：国際ジオシンセティックス学会日本支部  

FE analysis of plane strain compression tests on an unreinforced specimen and geogrid-reinforced sand specimens were conducted by nonlinear elasto-plastic FEM. The sand specimens was reinforced with 6 or 11 layers of geogrid. In the FE analysis. strength anisotropy, pressure dependency of strength, strain-hardening and -softening and shear banding (or strain localization) were considered for sand. The geogrid was modeled as a planar reinforcement in the plane strain FE analysis. By integrating the results from the FE analyses and the physical tests, the effects of reinforcement rigidity. covering ratio and interface friction angle on reinforcing effects and the dilatancy characteristics of reinforced sand were evaluated. A quantitative relationship was obtained between the reinforcement covering ratio of actual three-dimensional reinforcement and the equivalent interface friction angle in the 2-D plane strain FE analysis. Lastly, the effects and mechanism of the reinforced sand were evaluated based on the local stress paths within the reinforced sand.

DOI： 10.5030/jcigsjournal.13.218

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Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)  

CiNii Books

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Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)   Publisher：(株)総合土木研究所  

CiNii Books

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Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)   Publisher：(株)総合土木研究所  

CiNii Books

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Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (other)  

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Language：Japanese   Publishing type：Rapid communication, short report, research note, etc. (scientific journal)   Publisher：地盤工学会  

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Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)   Publisher：(株)総合土木研究所  

CiNii Books

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Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (other)   Publisher：国際ジオシンセティックス学会日本支部  

DOI： 10.11504/jcigstechnical1995.23.52

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Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (other)   Publisher：国際ジオシンセティックス学会日本支部  

DOI： 10.11504/jcigstechnical1995.22.2_30

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