Geosynthetic- Reinforced Soil Retaining Walls with a rigid facing (GRS-RWs) can be constructed by many kinds of backfill materials. But, in fact the backfill materials of most constructions are the sandy soil.
In Nagano, the JAPAN RAILWAY CONSTRUCTION PUBLIC CORPORATION are constructing Hokuriku-sinkansen car depot approximately about 100m wide and 2km long in use of GRS-RWs now. This construction has two special features, such as retaining wall on the very soft ground, the use of clay for the backfill material.
The result of soil/water coupled F. E. M. deformation analysis and the execution of G RS-RWs are reported in the paper.

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It is known that continuous fiber reinforced sand has anisotropy in deformation and strength characteristics which comes from its construction method. In this study, anisotropy of continuous fiber reinforced sand was investigated through box shear tests and simple shear tests with changing the angle of deposition.
Small amount of cement was added to continuous fiber reinforced sand to increase shear resistance and resistance to erosion. Box shear tests were also carried out.
The reinforcement works most effectively when direction of deposition coincides with the minor principal strain direction. Cement mixing increased shear strength, reduced deformation, and improved resistance to erosion.

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The friction on the upper and lower faces of the reinforcing mats were obtained by analyzing a reinforced retaining wall and an embankment with steep slope. The retaining wall had inextensible steel mesh and sand as backfill. The embankment had extensible HDPE geogrid and cohesive soil as backfill, and left about 5 months through the rainy season. Generally speaking, friction on the upper face acts in the forward direction and the friction under the lower face acts in the backward direction, and their distribution are not the same. The difference between the upper and lower faces results in the tension of the mat. The friction near the face of the wall acts in the forward direction. Soil constants related to deformation are closely related to not only stability but also deformation of the the retaining walls. Thus, the possibility of establishing new dsign methods for providing deformation of the retaining walls by taking into account of soil constants during and after the construction is discussed.

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For geotextile-reinforced soil wall, a prediction of deformation characteristic is important for a purpose of serviceability. Usually, this prediction is carried out by FEM. analyses. On the other hand, the purposes of this report are to predict deformation characteristics of geotextile-reinforced soil wall, to estimate tension distribution of geotextiles and to estimate earth pressure against wall, based on limit equilibrium method.
For convenience of analyses, the facing of the reinforced soil wall was adopted as discrete type concrete panels. It assumed the condition that the concrete panels were supported from the front side and removed the supports after filling was completed. A trial wedge method by linear sliding (method of Coulomb's earth pressure) was applied to simplify the analysis, based on an equilibrium condition for series of potential sliding surface that originated from connecting part of each panel. Internal stress and deformation behavior of reinforced soil wall were calculated.

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Many earth structures underlain by loose sand foundation have been damaged by the liquefaction of foundation during past earthquakes. Public Works Research Institute carried out shaking table tests on embankment model reinforced by geotextiles. In this test, reinforced embankment settled by liquefaction of foundation, but the settlement was smaller to some degree in reinforced model than in un-reinforced one. Although this reinforcement is not a positive measure for settlement reduction, embankments can maintain their shape. Therefore it can be expected that road and/or dike embankments maintain their function.
This paper describes the followings.
(1) Modeling of un-reinforced and reinforced embankments filled on loose sand foundation for two-dimensional seismic response analyses.
(2) Results of the analyses for liquefaction-induced deformation occurred under two levels of earthquake motion.
(3) Considerations on settlement reduction effect by reinforced embankment method and subjects for future research.

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Recently, geotextile is very often used as horizontal drains in constructing embankments with cohesive soils. In this case, it is important to select a geotextile and to design considering finite permeability of geotextile. Main purpose in this study is to make out standards of selecting a geotextile in using it as horizontal drains. In this paper, we suggest an analysis method, which is able to predicate distribution of pore water pressure in geotextiles and embankments in the case of using geotextile as horizontal drains.

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Sandbags are mainly used for structures like tempolary reinforced earth embankments because the structures from sandbags may be not expected so high in strength. The developed sandbags with a connection-device may be enable them to apply to large-scale structures.
This paper reports about the two kinds of developed sandbag with a connection-device, the trial balance calculation of the reinforced earth structure from sandbags with connection-devices and some fundamental tests on them.

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The authors succeeded in measuring strain of the very thin geotextile in the centrifuge scale model test for investigation the dynamic behavior of the reinforced wall with geotextiles. This type of experiments are in good accordance to the law of similarity, but it must be used with very small and thin reinforcement, due to the law of similarity. So we choose the very thin non-woven fabric for reinforcement. It is very difficult to measure strain of the very deformable material like thin geotextile. The selection of strain gauge and the adhesive is very difficult. Especially, in the measuring of dynamic strain like in our case, it can not be sured that result of measuring has high reliability by the normal technique of electrical strain measurement.
The authors obtained complete measuring result of strain of the very thin geotextile (non-woven fabric) in the centrifuge scale model tested under 30G of centrifugal acceleration using the wide range strain gauge attached to the thin non-woven fabric with special adhesive. These results were well compared to the calculation and other results of large scale model test.

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In pull-out tests of geomembrane in a cover soil, it is expected that failure pattern of the cover soil may be different with varying width of the geomembrane specimen and that ultimate pull-out resistance force for unit width may be different as a result. In this paper, the pull-out tests were performed varying width of the geomembrane from 1cm to 60cm under thickness of the cover soil of 10cm and 20cm. The followings are main conclusions.
(1) Under thickness of cover soil of 10cm and 20cm, the cover soil over geomembrane specimen with width of wider than 40cm moves as being accompanied by deformation of geomembrane. This results in ultimate pull-out resistance force balancing to frictional force between geomembrane and soil which was mobilized only lower surface of geomembrane.
(2) In the test where the width of geomembrane specimen with narrower than 10cm, the cover soil is stable against the deformation of geomembrane. The ultimate pull-out resistance force is larger than a value that was estimated so as to balance the frictional force mobilized both on upper and lower surface of geomembrane.

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The applications of geomembrane and geotextile are expanding on soil structures in railway, highway and so on. Thier typical functions are reinforcement and stabilization of soil structure, drainage and separation of soil and water. Regarding separation, penetration resistance of geosynthetics is one of the most important functions. However, there are no confirmed estimation method for penetration resistance. In this study, we developed the penetration resistance tester (PR tester) and by using this tester, we got the value of penetration resistance. And moreover, we got the master curve of penetration resistance, under the time-temperature superposition principle. By using this method, we can estimate penetration resistance under wide range of penetration rate.

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Current design methods of thickness of geomembrane liner consider only safety of its strenth and do not that of deformation that the liner might experience during its service life time. In this paper, a new design method taking account of deformation is developed which bases on simple elastic theory. Two design examples are also presented comparing with ordinary Koerner's method.
The followings are main conclusions. (1) The required thickness that guarantees safety of given deformation and strength can be expressed as t_re≥{2·D·E·(μ_U+μ_L)·σn}/σ_AL², where D, E, μ, σn and σ_AL are deformation, modulous of deformation, frictional coefficient between geomembrane and adjacent materials, normal burden pressure and allowable stress, respectively. (2) In order to gurantee large deformaton, structure which give lower friction between geomembrane and adjacent materials is favorable. (3) The proposed method seems to estimate thicker value than Koerner's method.

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The profile section of geomembrane-lined reservoirs was the liner coming up from the bottom of the pit, covering the side slopes, then running over the top a short distance. With regard to the stability of the running over, at the case of geomembrance runout only and no ancher trench at all, an exact knowledge of the interaction between geomembrane and soils was required. In this case, the the pull-out test was used to measue the interaction between geomembrane and soils. Then pull-out test were also carried out with various soiles and geomeranes.
As a results, some problems at the pull-out test of geomembrane was evident.

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