When a geotextile as filter is set in a ground for drainage, a decreasing of cross-plane flow performance of geotextile is expected due to a clogging associated with a intrusion and capture of soil particle. The objective of this paper is to consider a suitable geotextile filter to be hard to arise a clogging for fine-grained soils at a field site. This study was performed to focusing on a change of coefficient of permeability normal to plane on a kind of geotextile filter. A series of constant head permeability test on various geotextile filter was performed sandwiching in a geotextile filter between fine-grained geomaterial and gravel layer. This paper is discussed on a test method for an evaluation of the clogging property of getxtile filter, apparent opening size tests of geotextile and clogging properties of geotextile filters based on test resultes of a series of constant head permeability test on various geotextile filter.

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Sand of well quality is difficult to be supplied for horizontal drain to accelerate consolidationvelocity. On the other hand, pre-fabricated drain is recognized as the alternative major material.However the conventional drain design manual is insufficient in order to take the variousmaterials into consideration. In this paper, two layers horizontal drain model and its discretizationtreatment by differentiation for computing is presented to promote the horizontal drain design.After comparing the consolidation delay induced by the presented model with Yosikuni.s matresistance concept, and confirming approximation, the design procedure for horizontal drainusing pre-fabricated drain is presented for reduction of consolidation delay.

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Numerical analysis was carried out in order to simulate the development of large deformation that tookplace on the reinforced earth wall, which was located as a part of the Tottori expressway planned to passHyogo, Japan. Since this reinforced earth wall had experienced unexpected deformation of the wallduring construction, the wall was re-constructed twice. However, the wall deformation showed no sign tocease even at the final stage of the construction. Accordingly, countermeasures to re-stabilize the wallwere demanded. It was successfully simulated that subsidence of a 3-meter weak soil due to seepage flowwas responsible for the large deformation. A part of concrete panel wall was severely damaged due toextremely large pulling force of geotextile induced by the hammock state. As for the countermeasures,"grouting with slag system" was applied to fill voids of the backfill, and also to prevent furtherdevelopment of settlement in the weak soil layer. "Ground anchor" was also considered to achieve theprescribed factor of safety.

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In designing reinforced earth structures, apparent cohesion is often assumed to exist in the reinforced domain, by horizontally spreading geosynthetics within embankments. This assumption has been justified by Scholosser and Long (1973) who carried a series of triaxial compression tests using planner aluminum foils as the reinforcement. The authors investigate the reinforcing..effect in the triaxial compression tests performed by many researchers in the past, in which various kind of reinforcement material and testing procedure are employed. The result shows that the observed degree of reinforcement effect is considerably different from each other. The authors performed a series of triaxial compression tests using three types of reinforcement materials, each of which has a different tensile property. As the result, it was found that the apparent cohesion is clearly observed under appropriate conditions. The conditions where the apparent cohesion is generated is also clarified.

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Generally, geogrid mat foundation is used as the method of bearing capacity reinforcement. Geocell is also used for same purpose. We have been developing a geogrid-geocell coupling method to reinforce the foundation. In this study, we carried out some experiments to investigate the reinforce effect and the mechanisms for the method. At first, we experimentec on some reinforcement patterns to confirm the reinforcement effect. Next, stress distribution was measured by the seat type sensor. We calculated the quantitative reinforcement effect and the decreasing coefficient to develop the design method of the geogrid-geocell coupling system.

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The developments of design codes grounded on the reliability based design (RBD) are actively taking place in various part of the world today. RBD is considered to become the central tool of the design code developments. Under the situation, the importance of the reliability analysis of the structure in design increases though, study on seismic reliability analysis of reinforced soil wall is few. Therefore a study on analysis concepts for seismic reliability of geogrid reinforced soil wall has been conducted by authors. An approach of the seismic reliability analysis is introduced and future issues of the analysis concepts are discussed in this paper

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This paper shows the results of the dynamic centrifuge model test that is carried out to confirm seismic stability of the geotextile-reinforced soil wall which has a double facing system with a vertical layer to absorb the deformation between the facing concrete panels and reinforced backfill. In the test, authors make the 20-meters-high model of the wall under the 50G centrifugal field and investigate the influences of presence of the facing concrete panels and length of geotextile on the seismic stability of the wall. The structural characteristics of the wall obtained from this test are as follows; 1) the facing concrete panels and reinforced backfill behave integrally and are sufficiently stable, and 2) the wall has high seismic performance even if the length of geotextile is designed as unisometric arrangement.

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This paper shows the results of numerical analyses of dynamic centrifuge model tests to investigate the seismic performance of the geotextile-reinforced soil wall with a double facing system. Such reinforced soil wall has a thin vertical gravel layer between the wraparound face and facing concrete panels to reduce the earth pressure acting on the facing concrete panels from reinforced backfill. To investigate the influences of presence of the facing concrete panels and lengths of geotextile on its seismic performance, a related paper has reported the dynamic centrifugal results of a geotextile-reinforced soil wall 20 m high under a 50 G centrifugal field; this paper reports the results of dynamic finite element analyses of the centrifugal tests, and compares the numerical and centrifugal results to clarify the seismic performance of the geotextile-reinforced soil wall with a double facing system.

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In the embankment for the slab track of Shinkansen, there is a severe restriction of allowable settlement to preserve required performance. On the other hand, the construction method that expands the applicability of embankment material is needed to construct more economical embankment. Then we have developed the pile slab track soil embankment that is reinforced with geogrid against material with a lot of fine-grained soil, and can reduce settlement of concrete roadbed with soil foundation piles. We report the result of examination about the reinforcement effect of reinforcement material of embankment and soil foundation piles through shaking table tests.

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In this report, the results of field investigations on several types of reinforced-soil structures in North Tohoku area on the 2011 off the pacific coast of tohoku earthquake and tsunami were summarized. This repor focused on the structural damage of reinforced walls as well as embankments in south area in Aomori prefecture and Iwate prefecture. In this disaster, not only a very large earthquake but also the maximum tsunami was generated. As the results of field investigations, we can say that most reinforced earth walls were stable though some one received damages from the earthquake and tsunami.

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The rockfall protection wall using geotextile reinforced soil structure has high impact performance against the rockfall because it is flexible structure. The wall developed by us is classified into three types in considering of the serviceability limit state in proportion as rockfall energy. In the 2011 off the Pacific coast of Tohoku Earthquake, it is reported that several rockfall disasters of varying rockfall energy occur. After that, authors confirm that the wall located in the Tohoku district catches rockfall which exceeds the prescribed rockfall energy level of the wall. This paper reports the rock-fall protection wall using reinforced soil structure affected by the 2011 off the Pacific coast of Tohoku Earthquake.

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This study investigated composit geomaterial mixed with expanded polystyrol beads about the deformation and characteristics. The base material of composit geomaterial in this study used high moisture content volcanic cohesive soil (Kanto loam). The base material was mixed with super-lightweight EPS beads and with portland cement. This study aims at investigating the the deformation and characteristics of the composit geomaterial as well as accumulating the basic data of the composit geomaterial regarding the rational pavement design and clarifying its applicability to subgrade and filled-up ground in road embankment.

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The shortfiber admixture reinforced method is a reinforcement soil technology that makes to high value added by stirring and mixing the short fiber, and produces a more excellent ground material. Therefore, it is suitable for the having efficacy of the local surplus soil to instability. In this study, we carried out the unconfined compression and triaxial compression tests (consolidated undrained) using Kanto loam as a sample soil, and the change in the kind and blending quantity of the shortfiber reinforcement may examine the influence that caused it for the reinforcing mechanism of the shortfiber admixture reinforced soil in the present study (CU test), and the results were considered.

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A Liquefied Stabilized soil (LSS) is easy to occur a brittle failure as increased a strength due to an increasing of cement content. In this study, to examine the mechanical characteristic of LSS mixed with fiber material that uses the solidification material newly developed, a series of Consolidated.Undrained triaxial compression test was done to LSS mixed with fibered material that uses the solidification material for unusual soil and usual soft soil, and the influence on strength/deformation properties was examined. It was found that ductile property of LSS is improved as an increasing of fiber material, and reinforced effect for the damage by the shear.

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A simple measuring method of the creep upper yield value was examined by the short term increment method. There are various types on the creep properties of the geotextiles. The geotextiles contains it to the type that creep stages are not obtained from the type with primary creep, secondary creep and tertiary creep. Therefore, the creep test is not simple. We researched the creep properties of the type that creep stages are not obtained. As a result, the creep upper yield value that obtained by a simple measuring method was 75% of creep limit strength. The short term increment method can be used as a simple measuring method to obtain the creep upper yield value by improving test method.

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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.

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A lot of geotextile reinforced soils are designed, and constructed in Japan where the earthquake happens frequently. Therefore, the stability of the geotextile reinforcement soil at the earthquake is also very important. In general, the creep decrease of reinforcement is considered in the design of the ordinary condition. On the other hand, allowable strength of reinforcement is surcharged in the design at the earthquake. In this research, the test series were carried out to investigate the residual strength and creep performance of geogrid that is made from the continuous fiber of polyester. This paper describes the validity of the allowable strength of geogrid and proposes the extra coefficient of allowable strength of geogrid for seismic design.

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In Japan, sunshine carbon arc lamp (WS-type) has been used as a light source on accelerated exposure tests of geomembranes. But it is expected to replace the light source to Xenon-arc lamp with high irradiance (WX-type) because traditional WS-type test needs troublesome operations and so much time. In this study, to clarify the influence of light sources on accelerated exposure tests, 3 types of geomembranes (HDPE, TPO, and PVC) were treated with both WX-type and WS-type for various periods of time and their mechanical properties were examined by tensile tests. Surface profile observations and infrared spectroscopic analyses were also carried out to estimate their morphological and chemical changes in surface region. Results showed that WX-type exhibits higher accelerated effect than WS-type.

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This report is the investigation of the mechanical property of bending area of waterproof sheet applied in a coastal confined waste disposal site. Waterproof sheet, used in this investigation, was made of linear-low-densitypolyethylene (LLDPE). One dimensional tensile test and hydraulic bursting test were conducted at varied patterns as the number of bending, bending load and bending time. The result of the investigation, bending did not affect the mechanical properties of LLDPE sheet at the range of this test conditions.

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Strain gauges are often used to estimate the tensile behavior of barrier sheet subjected to deformation. As a rigidity of gauge is much higher than that of barrier sheet, the measured value of strain can sure smaller than that of sheet non-installed with gauge. In the paper, tensile tests for three types of sheet with different rigidity were conducted to evaluate the strain gauge constrain effect. As a result, it was shown that PVC sheet with low rigidity had larger constrain effect than HDPE sheet with higher rigidity. It is also found that constrain effect of the sheet with lower rigidity depends on deformation rate a bit.

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Long-term barrier performance of geosynthetic clay liners (GCLs) when exposed to acid rock drainage (ARD), which is one of the most severe and expensive environmental problems facing the mining and some construction operations, was evaluated. Free swelling, sorption, and a nine-month hydraulic conductivity tests on a needle-punched GCL against an artificial ARD (pH = 3) that contained Al, Fe, Cu, Zn, As, and Pb, were conducted. Free swelling tests showed that a high metal concentration and/or a low pH negatively impacted on osmotic swelling. Sorption test results provided information about the competition among metals, and the Na-bentonite capacity to sorb single metals and metalloids. Nine-month hydraulic conductivity tests demonstrated that pH, EC and permeability changes over time, due to metal sorption/release and precipitation (physical clogging). The hydraulic conductivity remained low during the test duration and was approximately five times lower when GCL was prehydrated with water before ARD permeation (1.1x10^-10 m/s) compared to the case in which prehydration and permeation were done using ARD (5.0x10^-10 m/s). In each case, effluents were evaluated and breakthrough curves were constructed to get information about the GCL attenuation capacity toward metals present in ARD. Considering that bentonite (or GCLs) has the potential to retain heavy metals present in solution, showed relatively low hydraulic conductivity under even extreme conditions, and is available in many parts of the world, GCLs seem to be one possible solution for ARD mitigation.

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This paper attempted to explain the relation between the surface temperature on the seam under heat welding with various welding conditions such as the material of the sheet, the preset temperature of the self-propelled heat welding machine, welding speed of the machine, and the result of friction test of the welded seam. From the result of the experiments which were conducted on the conditions of 10 oC of temperature, correlation was observed in the surface temperature on the welded seam of HDPE which were obtained from the thermal image and the friction test result. It was found that the welded seam became faulty if the surface temperature of the seam was lower than 50 oC. Furthermore, the heat transfer model for calculating surface temperature of the welded seam was developed and the model calculations and observations were compared. In the comparisons the model and observations differ only 3.0 percent.

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The geotextile tube for marine applications has been used around the reasons of construction performance with its simple execution. However, because this geotextile tube structures have not been constructed on the Japanese coast, this demand performance and construction system have not been established in Japan. In this study, the geotextile tube was constructed on the Seisho coast, Kanagawa Pref. This structure was required to have the stability to wave attack and the resistance to abrasion caused by coastal sediments. Coastal sediments were filtered under 30mm, and filled into geotextile tube with seawater using a sand-pump. The objective of this paper is to evaluate the construction and removal method, the stability, and the durability of geotextile tube.

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SThe Ministry of Land, Infrastructure, Transport and Tourism is working on developing new method to utilize geosynthetics for coastal protection. Concrete blocks have been used for constructing coastal facilities which aimed to protect the country from tsunamis, storm surges, waves and coastal erosion on the Japanese coast. Recently, geosynthetics is expected to be used for coastal protection, because the removability becomes to be required for coastal structures through beach nourishment. Moreover, demands for reduction of construction cost and improvement on ocean view were gradually increased. In this study, as an example of coastal structure which made of geosynthetics, "Sand filled bag - Cell type gravel mat" was proposed. In order to verify the actual workability on the coast, the trial construction in the company yards, the real test construction on the coast, and the observations were carried out periodically after the real test construction.

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Wastewater treatment was worked with the ECO-TUBE METHOD. While this waste water contained dioxin which occurred at the time of demolition of waste disposal building, inside of the eco-tube, filter-layer was formed with mud soil by being injected waste water in it repeatedly and filtration was enable. The dioxin density included in the treated water was able the environmental quality standard in 0.002 pg-TEQ/L.

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This paper presents the free swell and the hydraulic conductivity of geosynthetic clay liners (GCLs) permeated with organic chemical solutions of 1,4-dioxane and bisphenol A. The concentration level which deteriorates their swelling capacity and barrier performance was approximately more than 10,000 ppm for the permeation of singlecomponent 1,4-dioxane or bisphenol A solution. It was concluded that waste leachates in Japanese landfills do not have a potential to deteriorate the barrier performance of GCLs because the total organic carbon concentration of the waste leachates are as low as 100-1000 ppm.

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For the countermeasure against water quality purification in various water areas, a fence for water quality purification with high workability and applicability was newly developed, and the outlines, effect, and the example of application were shown. In order to verify the workability and effectiveness, a test construction using natural zeolite for a depurative was carried out in the moat of the Takashima Castle in Suwa City. The result confirmed that the construction of the fence can be carried out in a short time. The suitable circulation of water is maintained in the inside and outside of the fence. Improvement of transparency and turbidity of water, and adsorption of the total nitrogen of natural zeolite were confirmed.

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Deformation due to frost heaving has been reported on earth walls using geotextile materials in cold regions. Fullscale models have been constructed with a focus on replacement, drainage and heat insulation, and their strain and deformation were measured and compared with the conventional method. The outcome showed that strain and deformation caused by frost heave continued after thawing, and worsened when freezing occurred the following winter. In contrast, the replacement method proved to be the most effective approach for controlling frost heaverelated deformation of reinforced earth walls made using geotextile materials. It was also revealed that the technique was effective for controlling frost heave in existing reinforced earth walls with the installation of insulating materials.

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During 2004.2009 in Mito, Ibaraki, Japan, several locations of cut-off slopes of the Northern Kanto Expressway collapsed. These collapses were caused mainly by scour or erosion at shallow depth and piping phenomena at deep locations of sandy deposits underneath cohesive materials constituting cut-off slopes and by topographical characteristics,.. which caused collection of surface water from rainfall. Whenever a collapse occurred at these locations, traffic was blocked. Therefore, the highway function was compromised. The piping causing slope collapses at the deep location was triggered by water seepage through an intrusion from the surface, which had originated from continuous rainfall and heavy intervening rainfall after a side ditch failed because of seepage of continuous rainfall water intruding from behind. The remediation of collapsed slopes and countermeasures against the additional collapse expected in the future were conducted depending on the severity of slope failures. Particularly in more severely damaged locations, two kinds of gabion-type reinforcement were adopted at both shallow and deep locations of slopes; plastic pipes of two kinds for accelerating drainage were buried at both shallow and deep locations. Along with these countermeasures, high-density polyethylene pipes were installed along longitudinal ditches and grass was planted on the slope surface. An index for engineering judgment was proposed to determine whether these countermeasures will be successful or not. The countermeasures were finalized in 2009: monitoring for slope movement started and has performed continuously up to the present.

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In this study, focused on the cushioning function of EPS, impact absorption effect of the soil mixed with crushed EPS was investigated. Concretely, assuming a scene that a rammer was falling on the mixed soil, the effects of decreasing an impact acceleration for a falling object and an impact load for a bearing foundation caused by mixing of crushed EPS were examined. Then, influences of the deformation characteristics of the mixed soil upon these impact absorbency were considered. As a result, it was found that the impact acceleration and load were decreased by the mixture ratio of crushed EPS, and the decreasing ratio was almost in proportion to the decreasing ratio of deformation modulus of the mixed soil. And it was almost found that the decreasing ratio of the impact acceleration was correlated with the elastic deformation component originated in crushed EPS.

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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.

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