This paper presents the behavior of strength and secant modulus of 4 kinds of geomembrane, which is used for landfill liner at different temperature conditions. For all geomembranes, the relation between strength and temperature is almost liner, but the relation between secant modulus and temperature is exponent. The most important point for designing or application is that HDPE geomembrane and TPO geomembrane has extremely high modulus and high induced modulus at low temperature.

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When designing and installing the geomembrane liners made of HDPE, it is especially necessary to consider elongation or stress of the material produced by the change of temperature because of larger thermal expansion coefficient and Young's modulus of the material.
The author has measured solar absorption of black, white and green HDPE geomembrane liners by means of a spectrophotometer to identify effect of solar radiation intensity on the surface temperature of individual liners. Further the relationship between open air temperature and the surface temperature has been discussed.
Then highest surface temperature of the geomembrane liners in various locations in Japan has been surveyed from the data published by the Meteorological Agency, Japan.
As the results, the following conclusions are obtained.
1. It is the white geomembrane whose surface temperature is least affected by the solar radiation
2. No correlation can be found between the solar radiation intensity and air temperature.
When designing and installing the liners, it is possible to estimate the surface temperature of the liner based only on the solar radiation and air temperature at the construction site if such data are available.
Use of the white geomembrane is able to minimise the rise of surface temperature of the liner, which may result in updating the construction quality of installation of the liner.

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Geomembranes and geotextiles, recently, are becoming to be widely used as a component of liner system in waste landfill. The frictional characteristics on interface between geomembrane/soil and geomembrane/geotextile are very important factor to design liner's structure such as its anchorage or side slope angle. In this paper, convenient in-situ equipment to measure a frictional resistance between geomembrane/soil and geomembrane/geotextile was developed. The in-situ tests were conducted on two loam ground and on drain sand at construction site. The ground condition was prepared as natural moisture condition and submerged condition. The geosynthetics used included six geomembranes such as smooth HDPE, HDPE with spike, EPDM, TPO, PVC and reinforced CPE and two geotextiles such as continuous nonwoven and stapled nonwoven. As the results, it is found that the ratio of frictional coefficient estimated at submerged condition to one at natural condition is about 70-80% for loam ground while it is 90% for drain sand. The frictional coefficients between smooth surfaced geomembrane and stapled nonwoven geotextile estimated at in-situ tests is good agreement with the relationship between normal stress and shear stress obtained by direct shear tests in laboratory.

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For an investigation of an anchorage ability of geomembrane liner buried in trench filled with concrete, the field model tests were conducted. Test parameters, such as a size of an anchor trench, a type of geomembrane, cut slope or filled slope, with and without geotextile, were considered. A larger anchor has larger ability, but the pulling force when concrete anchor starts to move up, is almost equal to the concrete weight. And the pulling force at the case without geotextile is greater than the force with geotextile. So, a geotextile should be used carefully at the anchor trench. And the soil strength is also important to designing anchorage trench structure, because the anchorage ability thought to be effected by the soil strength.

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This paper presents the results of fundamental mechanical properties of fiber-reinforced soils investigated by an unconfined compression test. Three kinds of reinforcement materials tested were glass fiber, rubber net and polyethylene net. Two types of soils used in a series of tests were the mixtures of fine Toyoura sand and Kisarazu pit sand mixed with Kaolin clay, respectively, and they were compacted in their optimum conditions.
It was found that the reinforced soils tested in this experimental works made some improvements of their mechanical properties. All reinforced pit sands demonstrated both high moduli of deformation and remarkably high peak strength, and the glass fiber reinforced sands improved their residual strength. The effects of reinforcement material, shape, size and mixing rate on the mechanical properties of the soils were also discussed in detail.

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It is known since old times that the usage of a flexible fabric as a tensile material for confining granular materials is one of the effective reinforcement methods. In this fundamantal study a series of unconfined compression tests on geofabric reinforced cylindrical sands was carried out to investigate the interaction effects between reinforcement materials and soils. Moreover its theoretical evaluation method was proposed.
Experimental results showed that the confining effects of geofabrics depended on the tensile properties and the the moduli of deformation were affected by its strain level. It was also found from a theoretical consideration that the quasi-lateral confining pressure was directly proportional to the internal friction angle of the soil.

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Earth reinforcing method using geotextile which has hydraulic function is effective for the constructing embankment using clayey soils. In the design of reinforced embankment, it is important to evaluate the pullout resistance of geotextile in the soils. However, the pullout test method using compressible clayey soils has not been examined enough. We developed new type test apparatus to make clear pullout behavior of geotextile in the clayey soil, and examined its applicability by conducting laboratory test.

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A number of small scale 1g laboratory model footing tests were conducted to investigate the factors contributing to improvement of bearing capacity of soft clay reinforced with geotextiles. The present paper investigation indicates the following: (1) the geotextiles with high frictional force are effective for bearing capacity improvement, (2) improvement effect of geogrids is exerted by restrainment of edges and by combining the unwoven geotextile. (3) the effect of sand mat overlaid on soft clay on bearing capacity improvement is most exerted in the combination with geogrid.
The numerical analysis as well as the experiments prove that combination of geogrid with sand mat is particularly useful for bearing capacity.

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Preloaded and prestressed (PLPS) reinforced soil method, recently proposed, aims to increase substantially the stiffness of a geosynthetic-reinforced soil retaining wall by vertical preloading and prestressing. Its mechanisms are described. Rheological properties of the backfill soil, which are essential to the method, were determined from triaxial tests. Field full-scale model tests with gravel backfill during preloading and under prestress for more than a year is presented. The first practical project of PLPS reinforced soil pier for a railway is described. Most part of the initial prestress remains in a PLPS reinforced soil structure for at least one year under a static loading condition. Preloading makes the reinforced soil stiffer and elastic and introduces lateral tensional prestress in the reinforcement. A method to apply preload and prestress to a reinforced soil structure is established.

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This paper proposes a limit design technique for a slope and retaining wall reinforced by geotextile, which is fundamentally based on the initial stress method for nonlinear stress-strain analysis in FEM, aims to fill a large gap existing between FEM and LEM (Limit Equilibrium Method) which is a traditional design technique also in earth reinforcement problems. The proposed procedure employs Mohr-Coulomb and Coulomb yield criteria respectively for soil mass and friction interface. By assuming a linear elastic response before yielding and a non-associated flow rule after yielding as a stress-strain relationship, the proposed procedure provides a definite collapse mode similar to a potential slip surface assumed in LEM. It is difficult for LEM to consider the kinematical condition at failure and the stiffness of material. The proposed procedure enables to compensate for most of these defects in LEM, because the procedure is based on FEM. This paper reports the result of applying the proposed procedure to a hypothetical stability problem of a slope reinforced by geogrid, and to an actual test embankment for reinforcement method.

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It is reported that the reinforcing method by geotextile is effective for construction of embankment using high water content cohesive soils. However, the reliable design method has not been established yet. In this paper, the design method is proposed based on the consideration of its drainage effect and reinforcement effect.

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This paper deals with six cases of shaking table tests on geosynthetics reinforced earth walls, in which reinforcement length, embankment height, wall surface gradient, wall surface rigidity and input seismic wave were varied. And the test results were compared with the results of pseudo-static analyses. The following results were obtained.
(1) The slip surface, in case of the partition-type wall, came out from the outer area to the lower layer of the reinforced zone. Under additional vibration, the whole reinforced zone worked as an integrated body and moved toward the front side with the rear portion transformed into a wedge shape. In case of the integrated wall, as the deformation of the wall was restricted, large bend occured at the upper tip.
(2) In case of the partition-type wall, the earth pressure and the reinforcement tension were larger at lower or nearer to the wall surface. In case of the integrated wall, both of these values were smaller compared to those of the partition-type.
(3) The earth pressure at the rear of the reinforced zone, the peak occurred twice in one cycle in case of large accelerated vibration.
(4) From the results of the comparative studies with the pseudo-static analyses, the present design method had a certain degree of tolerance for safety against total collapse. When restoration is not required, the importance of the setting of safety factor for the limit usable deformed state was pointed out.
(5) For the reinforcement tension distribution, the design value was larger than the observed one at the upper portion of the embankment, but on the lower portion, the opposite tendency was obtained with the mid portion occurring as a borderline.

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The embankment of JR-Tohkaidoh line beween Settsumotoyama and Sumiyoshi was destroyed by the earthquake of Hyogo south area on January 17th 1995. The line runs east and west on the embankment on the formar river lied north and south.
The embankment was supported mainly by the stone-piled retaining wall. The face of slope covered with concrete blocks was destroyed completely. Most of the retaining walls were clacked and, above all, some of them were devided in two pieces.
For the purpose of opening the two inside lines earlier, which was little damaged, and besides restoring the trucks of the two outside lines, the erection fixture was done. It obliged the embankment to be shut out by sheet pile. In order to improve this problem, we decided to take RRR method, which effected sufficiently also for this earthquake, and as the length to lay the reiforced segument could not be enough, we adopted radish-anchor method.
This report shows the guideline of our restoring this damaged embankment.

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As shown Fig. 1, both up and down lines of Hukuchiyama between Amagasaki and Tsukamoto run at the distance of about 0.5 kilometers at maximum each other. As part of the project of twolevel crossing (railway and road), new embankment is constructed on both sides of the previous embankment of the down line to bind the both up and down lines together.
As the place of construction is narrow and close to private houses, the condition of construction is sever; not in use of big machines, less noisy and less vibration and dugging as little ground as possible.
And besides, though new embankment would be about 7 meters tall, the subsoil is poor: N=2∼3. Thus, it would have been unavoidable to drive piles, if the usual retaining wall was constructed. This is difficult on such a narrow space.
To overcome this difficulties, we drivel soil cement colums by small machines and constructed the reinforced embankment.
This new embankment is confirmed to be resistant to earthquake, as it was not suffereded from Hanshin-Awaji earthquake. Our method in more detail is shown below.

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