By the 1995 Hyogoken-Nambu Earthquake, a number of permanent important engineering structures were seriously damaged including the retaining walls (RWs). A number of conventional type masonry and gravity-type RWs was particularly serious damaged. The geotextile-reinforced soil RWs that had been constructed for a total length of about 2km behaved very well. A geotextile geotextile-reinforced soil RWs located in one of the most severely shaken areas was deformed only slightly. This paper describes the seismic performance of the geotextile-reinforced soil RWs, its back analysis, and an outline of a new design method against high seismic loads.

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Geosynthetics of many types such as nonwovens and geogrids have been used widely as reinforcements for embankments. One of these materials, a geosynthetic based on a high strength web shaped material, was installed to secure the stability of the embankment until the soft ground could get the sufficient strength due to consolidation. And it has been used in order to reduce the cost of construction of an expressway.
The stress-strain behaviour of the material has been examined in the laboratory and the movement of the reinforcement in the embankment has been measured.
This paper describe the relationship between the designed value and the observed behaviour of the material in the embankment together with the laboratory results.

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Theoretical study of Geonet replacement method has been carried out since the twelfth Geosynthetics Symposium in Japan. We have gotten a deformation equation and a tensile stress equation. In this paper, we compared the calculated results by obtained equations and the observed results. These equations can have a good approximation. Furthermore, we tried a parametric study using the tensile stress equation. As a result, it is found that a tensile stress of geonet was influenced seriously by width of geonet and undrained shear strength, otherwise less by density between replaced soil and soft ground.

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In construction of a road on the soft ground, the subgrade in general is constructed using a replacement method or improvement works. However, they must be considered from the standpoint of environmental influences such as generation of surplus soils resulting from the replacement or soilidification agents to be used for improvement works. The construction of a road pavement on the soft ground using geosynthetics whose raw material being synthetic high-molecular weight materials have already been established in foreign countries. In Japan, it is also confirmed that geosynthetics is being employed as a temporary treatment in the road construction stage. In this study, we have accumulated actual construction works and analized them for the purpose to clarify the scope of so that a foundation for practical design and construction method can be established finally. This report describes the status of actual construction works and conditions after the construction in the subject of an experimental construction.

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Recently, compared with Subgrade Reform Method and Soil Replacement Method for road construction, application of geosynthetics for the separation material between soft subgrade and base course seems to be preferable. In the early stage of pavement construction, destructive forces caused by heavy constructive machine work on geosynthetics are very large and the damage of geosynthetics would be considerably. Therefore, survaivability of strength of geosynthetics must be evaluated. A standard testing method to evaluate the damage of geosynthetics during construction has not established yet. Geosyn-pave society investigated two testing methods using conventional roller compactor or repetitive fatigue testing machine proposed by ISO. As the result, it was found that nonwoven fabrics are damaged less than woven fabrics. As the subsidence of base course material increases, the damage of geosynthetics becomes severely. In these testing methods, geosynthetics are affected by different destructive forces.

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In September 1998, in the portion of regional highway Toga-Kawai-Sen Daikanba area, Toga-mura, Toyama in Japan, the highway shoulder failure was happened by typhoon. As a counter measurement method, the mechanically stabilized earth wall was considered for a reconstruction method because of the difficulty of carrying on heavy materials and equipments. The ground was stable but to keep the embedment length of geosynthetics, an excavation of the backside ground seemed to be necessary. To reinforce deficient tension resisting force of geosynthetics, the reinforcement method that is to connect geosynthetics and rock bolt installed to the ground was proposed. In this paper, first of all, the design method of the mechanically stabilized earth wall, which is considered about restraining effect of rock bolt, is described. Secondly, the connected structure of rock bolt and geosynthetics is described. Finally, the monitoring plan in the construction is described.

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Ten years have passed since the soil reinforced method with geosynthetic was introduced for the first time into railways. After Railway Technical Research Institute (RTRI) developed the geosynthetic reinforced retaining wall with rigid facing, vertical embankments have been constructed increasingly in place of retaining walls of reinforced concrete structure. Furthermore, the first prototype reinforced soil pier was constructed for a temporary commercial line by the vertical preloaded prestressing method (PL·PS) recently.
In actual cases of this reinforcing method, there are various styles of soil embankments, including those constructed by the methods different from standard and made use of the features and advantages of reinforced soil. This paper introduces such cases and researches on the application of geosynthetics for railway structures.

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The procession method for geogrid reinforced soil wall at face of slope has been changing from using vegetation sandbag to using steel facing unit (L-type steel frame). At first, the reason of it is the problem of work saving and appearance. Therefore, the usage records are certainly increasing because of its functionality. Considering about the role and efficiency as the facing unit in reinforced soil wall, how effectively the facing unit gives the confining stress to the embankment is important. Moreover, considering about it is the permanent structure, how the long-term durability will be ensured is also important. By the measurement results of the stress, which affects on geogrid and facing unit, in the actual construction of reinforced soil wall, the efficiency and functionality of L-type steel facing unit are reported.

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By the compressive prestress, the restraint effect of soil, reinforced by geosynthetics, increases and the ductility of the reinforced earth improves. In the previous study, the efficiency of the compressive prestress for the restraint effect of soil was tested by using several different types of reaction plates and wall facing unit. However, the construction and design method of the compressive prestress in the embankment has not been confirmed at the present. In this test, as the small-scale test, the effect for the stress in earth and the workability of the influence of quality, size and direction of reaction plate were tested. In this test, following results were confirmed;
The bending rigidity influences to the stress propagation effect in earth.
The efficiency of the compressive prestress for the restraint effect of soil increases.
The some improvement is needed for workability.

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The capability of the rockfall protection MSE-Wall (Mechanically Stabilized Earth Wall) was confirmed by actual rolling rock test in June 1998. However, it is difficult to comprehend about capability of the rockfall protection MSE-Wall except the same test condition and it is also difficult to do appropriate design for several cases of load because there is a little assurance about rockfall protection MSE-Wall. Therefore it seemed to be needed to rerun the actual test for analysis, and determine the parameter of physical factor of the rockfall protection MSE-Wall for suitable desgin. In this paper the determination of analytical model and physical factor of the Rockfall Protection MSE-Wall that matches test results is described by dynamic response analysis using finite element method.

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Centrifuge model tests were conducted to study the behavior of geogrid reinforced embankment during earthquakes. In this study, an attempt was made to discuss the effects of length and spacing of geogrids on the behavior of the reinforced embankment. It was found that displacement of reinforced zone was caused by the combination of sliding and shear deformation of the zone. The larger sliding took place in the case with the short geogrid for reinforcement irrespective with the placing. Spacing of geogrid mainly affected the shearing deformation.

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A series of tilting tests, shaking table tests with regular wave and irregular wave were carried out to investigate the seismic stability of the reinforced-soil retaining and conventional retaining walls. The seismic resistance of reinforced-soil retaining wall models was higher than that of the conventional retaining wall models which agree with the damage observed after Hyogoken-Nanbu earthquake. The experiments revealed that by extending the upper reinforced material, the seismic stability of the reinforced-soil retaining wall could be improved more effectively than by extending all reinforced material. The reinforced area showed a shear deformation and the failure plane did not penetrate into the reinforced area which is not considered in the current earthquake resistance designing procedure.

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Static cyclic horizontal loading tests were performed on small-scale models of preloaded and prestressed (PL/PS) reinforced soil bridge pier to investigate effects of using tie rods on the seismic stability of the structure. The tie rod tension increases when the height of backfill increases, and decreases when the height of backfill decreases. As a result, when a PL/PS structure exhibits bending deformation by seismic loads, the tie rod tension increases to effectively restrain the deformation of the structure. However, if the initial level of prestress is too low, the confining pressure on soil becomes very small at the elongation side of the bending motion, resulting into large soil deformation, and it causes large residual settlements by shaking and a large reduction in the tie rod tension. Therefore, for the effective use of tie rods to increase the seismic stability of structure, it is important to keep a high prestress level.

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Preloaded and prestressed reinforced soil structures can have very high stiffness exhibiting very small residual settlements during service. To study the seismic stability of the structure, we performed shaking table tests with various values of preloading and prestressing. The equation to give the resonance frequency of PL/PS reinforced soil bridge pier is proposed. It is shown that preloading has effects in making the axial displacement in the side zone of backfill during cyclic loading more elastic and thereby in decreasing the residual displacement, and the prestressing has effects in increasing the resonance frequency and when the structure does not resonate, thereby in restraining the residual settlement of backfill during shaking, showing the importance of introducing sufficiently large prestress. It is shown that when the structure does not resonate, the residual settlement of PL/PS reinforced soil structure could be negligible and even when the structure resonates, PL/PS reinforced soil structures would not collapse with sufficiently high prestress being maintained.

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Large deformation in a geogrid-reinforced embankment occurred during the construction of it. This phenomenon was caused by banking materials with high water content.
Immediately the top of embankment was removed so that the situation could not get more serious. As a permanent measure, counterweight fill using cement stabilized soil was adopted based on soil tests and stability analysis.
This paper reports a series of circumstances from initial conditions, observed behavior to investigation, analysis and constructional measures.

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The reinforced soil with retaining wall on a soft ground is predicted to considerably settle in different modes of deformation adopted orders of construction process and characteristics of geosynthetics.
This paper describes the differences of displacement, stress conditions of retaining walls and geosynthetics in the soil by using the result of finite element analyses and measured data.

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Vertical preloading and prestressing (PLPS) of geosynthetic-reinforced soil structure aims at substantially increasing its stiffness. The first prototype PLPS reinforced soil pier for a railway was constructed in 1996, and has been opened to service for more than 2 years. Long-term measurements for more than 3 years have been made, and the behavior at train passing was measured just after opening to service and after 2 years of service. The measurement results are described.

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Large settlements have often taken place in the backfill in back of bridge abutments during previous earthquakes. To alleviate this problem, it is proposed to geogrid-reinforce the backfill in back of conventional type bridge abutment and further to construct geogrid-reinforced soil retaining walls as bridge abutments. Shaking table tests were performed on small models of; 1) conventional RC abutment with unreinforced backfill; 2) grid-reinforced soil retaining wall as an abutment; and 3) and 4) conventional RC abutment with reinforced backfill, with and without reinforcement layers attached to the back of the RC structure. The importance of attaching reinforcement to the back of the RC structure in keeping the residual deformation and displacement of abutment small was demonstrated. It was also found that the reinforced soil retaining wall has a high seismic ductility, while the deformation should be reduced by some measures, such as preloading and prestressing.

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This papers presents the appropriate seismic resistant design of geosynthetic-reinforced embankments against large earthquakes. The analyses method is based on a equation of rotational motion for soil block assumed by a circular failure plane. A series of parametric studies to determine the permanent displacements of reinforced embankments was conducted by varying the soil materials parameters, the height of embankments, the soil materials parameters, the layouts of reinforcement and design earthquakes in depicted in design standards of railway structures recently revised.
As a result, the combined method of short and long geosynthetic-reinforcements is satisfied for required seismic performances. Short geosynthetic-reinforcements with low strength are spread near slope in each layer at vertical intervals of 0.3 meters. This existing method is used for layer compaction depicted in design standards. Longer geosynthetic-reinforcements with high strength are spread over in embankment at vertical intervals of 1.5 meters.

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Reinforced sand shows larger dilatancy associated with a larger volume of shear zone in direct shear tests, compared to unreinforced sand. It is likely that multiple shear bands develop forming a thicken shear zone, resulting in larger dilatancy. Air-dried sand specimens reinforced with phosphor bronze strips installed perpendicularly to the shear direction were tested by using a medium scale direct shear test apparatus. The test results were analyzed with a new mechanical model using estimated thicknesses of shear zone as one on the major input parameters.

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Various geogrids are widely utilized now. Material properties as well as pullout resistances of respective geogrids are investigated. However the properties of those geogrids are rarely compared each other. In this report, the material properties and the pullout resistances of eleven major geogrids used in Japan are summarized and discussed based on the data presented in the reports published by Public Works Research Center. Pullout resistances and strains at pullout failure are correlated with the properties of geogrids, tensile strength and tensile stiffness for example.

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When using Geogrid, we design or construct embankment, it's important to understand the interrelation between Geogrid and the soil.
The previous test results were based upon a pull-out test in room and a box shear test. The test environment was, however, artificial and so did not take into account the true compaction conditions found outdoors. We therefore conducted a pull-out test determine the specific friction stress of Geogrid and its embankment under its usual working conditions.
A report was compiled detailing the abstracts of the test and its results.

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The authors have experimentally examined the reinforcing effects in geogrid-reinforced soil and evaluated it quantitatively. As a result, it was made clear that the reinforcing effects are expressed by the sum of the tensile effect and the confining effect. The tensile effect is due to the tensile force of geogrid. The confining effect is the effect that the geogrid is placed in the soil and restricts the deformation of soil. Therefore an additional confining stress is induced.
In this paper, the confining effect was introduced into the design method to decide the arrangement of reinforcement, referring to “Design and construction manual of geotextile-reinforced embankments published” by Technical Memorandum of Public Works Research Institute. And some examples of calculation results were shown. In conclusion, the proposal method can reduce the amount of reinforcement about 10-30%. And some points which are requested to use the proposed method were mentioned.

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A geocell which is made of a three dimensional cell structure using geosynthetics materials to confine cohesionless soil particles in the plane direction is one of the reinforced earth construction methods. The geocell having a slab-shape mattress structure aims to provide a bending rigidity, to increase the strength and to spread the stresses downwards the subsoil ground. It is known that the slab effects of geocell depends on various factors of reinforcement materials and filling soils.
In this study, three types of 5cm height cells having triangle, square and hexagonal cross sections are tested in order to investigate the fundamental properties of geocell. The geocells filled with air-dried Toyoura sand which is compacted in the specified density are compared with non-filled cells. Uni-axial compression tests in the cross-plane section are carried out to examine the influence of cross section size, number, tolal area of side wall, total area of cross section of cells.
From the test results it was found that the reinforcement effects were increased with the number of cells because of increasing the restraint area of side walls, and increased with the numbers of corner which disperses the concentrated stress. Moreover it was confirmed that the total area of geocell distinctly influenced on reinforcement effects.

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A short length fiber-reinforced soil is classified as one of the fiber reinforced earth construction methods. The dispersed fibers within the soils confine the deformation movement of soil particles. These fiber reinforced earth methods can be employed for the effective usage of unstable in-situ soils and problematic disposal geotechnical materials, and be able to add new and surplus properties to the original soil. However the reinforcement mechanism and their influence factors of the short length fiber-reinforced soil are not sufficiently revealed so far.
In this study, the effects of length and diameter of nylon-fiber reinforcements on mechanical characteristics of Toyoura sand, Kaoline clay and their mixtures are investigated using both shear box testing and unconfined compression testing.

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The reinforced embankment by GHD materials with steep slope was completed in 1996. After then, monitoring system has been applied to analyze the stability of this mound for about three years. Measured data show that it keeps so stable to encounter little deformation and no sign damaged by rainfall. However, it is suspicious that rain may infiltrate from the surface of embankment into the inner through the group of GHD installed horizontally. Since this causes the strength of soil to change weak and its volume to swell, long term measurement was performed. In addition, enforced infiltration test was carried out. This paper shows stability condition of the slope using the measured data.

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Recently, construction of high and steep earth fills using a high water content-cohesive soils is a common practice. Because geocomposites which have sandwiched structure of woven fabric between non-woven fabrics have over the tensile strength of geogrids of woven fabrics and also having the drainage effect of non-woven fabrics. However, current design methods of nonwoven fabric-reinforced earth fills have considered the drainage function only. This paper presents an experimental study on geocomposites-reinforced steep earth fills using Kanto Loam. Comparing both no-reinforced and geocomposites-reinforced earth fills varying, consolidated times, the efficiencies of the geocomposites as drainage and reinforcing material are judged.

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Recently developed geocomposite has sandwiched structure of woven fabric between both non-woven fabrics and has over the tensile strength of geogrids of woven fabrics and also having the drainage effect of non-woven fabrics. However, current design methods of non-woven fabric-reinforced earth fills have considered the drainage function only. Therefore, this paper proposes a new design method of earth fill structures considering the reinforcing effect together with strength increase of the volcanic loam caused mainly by drainage. This paper considers also the soil-fabric interaction and the effect of geocomposite on the final performance of steep earth fill structures.

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The paper presents the results of four large scale field model tests on steep faced (1V:0.6H) Kanto Loam embankment reinforced with planar nonwoven geosynthetics. Two embankments were unreinforced, one being loaded immediately after construction and the other was loaded to failure after 20 days of field compression. The other two embankments were reinforced, respectively with three equally spaced geotextle layer and they were tested under spread footing. All these four embankments were fully instrumented to measure the lateral slope deformation, vertical settlement, pore pressure distribution and tensile strain distribution within the reinforcement. The unreinforced ones collapsed at almost same vertical load but due to pre-compression, settlement was markedly reduced. The load carrying capacities of the reinforced embankments became almost doubled at little higher footing settlement and the effect of pre-compression was significant in increasing both embankment stability and efficiency in the reinforcing action of geotextile. The geotextile layers being laid unrestrained at the edges, they showed increasing tensile strain inside with higher loading and none of them failed during the load tests.
A series of laboratory physical model tests have been conducted. The effect of nonwoven as well as composite geotextile in addition to thin granular mat in between Kanto loam and geotextile, have been found very much significant. Test results reveal that use of geo-composite ensures significant stiffening effect of the reinforced-sand mat-Kanto loam.

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Mechanical properties of geosynthetics required for improving bearing capacity and increasing stability of slope of soft cohesive soils are summarized as: (1) high strength and stiffness to follow the large deformation due to applied loads, (2) adequate frictional resistance at the interface of geosynthetics and soil, (3) long-term permeability and transmissibity. As one of the geosynthetics which may suit the above-stated requirements, the authors have recommended the use of composite unwoven geosynthetics. It consists of high strength woven geosynthetics pasted within unwoven varieties. This composite geotextile can act as reinforcement as well as drainage media when used within soft soil. The advantageous features of this geo-composite material have been proved in laboratory small-scaled model tests. Test results of the improvement of bearing capacity of soft clay and increase in slope stability of embankment made with volcanic ash cohesive soils (called Kanto Loam) are reported. It is emphasized that placement of thin sand mat in-between geo-composites and soft cohesive soil is more effective for attaining those requirements, particularly for maintaining permeability and transmissibity of the materials when it is used for increasing stability of embankment by Kanto Loam.

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Today, there are a number of contaminated sites that have soils contaminated with oils and organic solvents. Bioremeidiation is one of the relatively few methods for actually destroying organic contaminants other than incineration and few chemical methods. In this study, in order to discuss the effective application method of the geotextile filters for the remediation system, laboratory test and model test were carried out. As a result, it was investigated that the effect of moving of soil particle and collection of Ca on the geotextile filter.

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Horizontal geosynthetic drain such as geotextile, geotextile-related product and geocomposite are employed for constructing of highly moistured clay embankment and drainage of seepage water in the existing embankment.The usage of the geosynthetic drain materials is being increased because of the shortage of natural filter sands.
In order to investigate fundamental properties of transmissivity (in-plane permeability) and permittivity (cross-plane permeability) of horizontal drain materials embedded in the embankment, a series of laboratory box permeability tests under different water heads and overburden pressures are conducted using a spunbonded geotextile, Toyoura sand and Kanto loam clayey soil.
It was found from the test results that there was a constant ratio of in-plane permeability to cross-sectional one, and the transmissivity was affected by the decrease in the thickness of geotextile under surcharge loads.

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Rising needs for environmental marine sand preservation forces us to substitute the supply condition of vertical drain from the plastic board drain (PBD).
Paper drain (PD), prior material in the market to PBD, was imported in Japan in 1963. It was allowed to have the function as a material for vertical drain. However, accumulated experiences proved PD materials have relay effect on consolidation velocity caused by deterioration of material. Therefore, since the paper the restriction as the drain material, development of PBD has been promoted to research. As the results of this investigation, composite type of PBD were produced.
In this paper, reviewing the history of development from PD to PBD, and summarizing the properties for material and remained item, directional research for PBD will be proposed.

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The CAES-G/T requires storage of compressed air at a maximum pressure of around 8Mpa. With a view to achieve practical CAES-G/T system, air-tight lining structure was proposed and have been investigated. The properties required for air-tight lining structure are that they should be sufficiently pressure-resistant and air-tightness. Among some polymers we selected isobutylene-isoprene rubber for most adaptable material. In addition, to verify the applicability of air-tight lining structure, In-situ Storage Test was performed using a test cavern. The results have demonstrated that the air-tightness requirement was met, but measurements showed evidence of a slight degree of leak from the air-tight sheet. Therefor, after the completion of the test, the facility was removed to clarify the causes of problems and to establish the appropriate measures to improve the design. This paper reports a study of selection of air-tight sheet and results of In-situ storage test.

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With the revision of laws for improving waterproofing capabilities of ordinary waste final disposal plants, various waterproof structures and materials have been proposed. This cut-off sheets has been developed based on an epochal idea. Made of the material with self-repairing waterproof capability, it reacts to damage through direct contact between the damaged part and waste water, and repairs the damage by itself. This paper describes the results of laboratory tests of the membrane conducted in the course of its development.

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A new repairing method development for the damage point of impervious sheet from leaking, with out drying the water using a geosynthetic clay liner of bentonite layer which adhesives to geomembrane. When the geosynthetic clay liner is placed to the damage point, its swelling, high liquid limit and effective power by the sandbag brought plastic deformation. It is conceivable that these total factor and of it's adhcsives caused non-permeability of the damage point. At he execution scene using this method, it is confirmed that the water leaking had reduced 1/6, cnnparing before execution.

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Field pull-out tests have been conducted for the models of actual sized concrete anchor in order to investigate its anchorage ability of geomembrane. But the value of adhesion between geomembrane and concrete is not found accurately. In this paper, the authors, first, concreted the surfaces of geomembrane varying its contact area, then pulled the geomembrane out of concrete. They also conducted the pull-out test for the geomembrane overlaid by the nonadhesive concrete within a trench. These results are compared with the results tested in the field. The following conclusions are found;
1) Maximum adhesive strength per unit area is about 10kN/m².
2) The behavior such that the anchor concrete moves up is caused through the adhesive force between geomembrane and concrete.

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Geosynthetics materials for the sealing structure of water and waste disposal are increased. It is some reported breaking the geomembrane by the dissimilarity subsidence of a basic ground and generating the crack.
Authors executed the experiment to imitate the constructed geomembranes until breaking. Based on the results, we considered between the influence on the esparsion strain distribution and thickness of geomembrane and shape of the voids of basic ground.

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This study focuses on the impeding behavior to movement of water through various punctures of geomembrane-supported GCL (GS-GCL) specimens. Permeability tests were conducted for the specimens with lacerations or different diameter perforations in tap water under air pressures varying up to 294kPa overburden. For a sample disk having a 5-cm laceration in length, it was observed that the bentonite layer of the lacerated part began to absorb water rapidly and then drainage decreased quickly and established self-healing, although the specimen showed an appreciable amount of drainage for immediately very short time after the overburden pressure was increased. Specimens with perforations of 1cm in diameter or less were completely filled with swollen bentonite gel giving a hydraulic conductivity of <1×10^-10cm/s. The sample disk having a perforation of 2.5cm diameter also obtained a hydraulic conductivity of <1×10^-10cm/s, but filling the perforation with the swollen bentonite gel required for a longer time. Results appear that self-healing function of punctured GS-GCL will seal a perforation of diameter not exceeding 2.5cm. It has been found out that plastic deformation and extrusion of the swollen bentonite gel layer, to fill and seal the perforation with its own gel, is a function of time and overburden pressure.

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Hydraulic conductivity performance of a geosynthetic clay liner permeated with inorganic chemical solutions is discussed. Although GCLs are expected to be applied to bottom liners and/or covers to contain wastes in landfills, limited data on the chemical compatibility are available. In this study, the brief literature review as well as the hydraulic conductivity test results are presented. The literature review shows there are some significant factors affecting the hydraulic conductivity values on GCLs permeated with chemical solutions. For the experimental work, hydraulic conductivity tests were conducted on a needle-punched GCL with inorganic chemical solutions by using flexible-wall permeameters to assess the effect of the concentration, pH, and other factors. Experimental results showed (1) a significant increase in hydraulic conductivity occur between 0.01-0.1M in concentration for divalent and trivalent cations, (2) monovalent cations has less effect on hydraulic conductivity than divalent cations, (3) the hydraulic conductivity is affected by both pH and cation concentrations, and (4) an excellent agreement between the hydraulic conductivity and free swell volume is achieved.

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It is important to examine the performance of Geomembranes (GMs) used for the surface lining system of reservoirs in the actual site condition constructed as a water-proof system, and to evaluate it under the operated condition. In this paper, each technical problem of the following three case studies into which GMs were used on a large scale was discussed. A regulating reservoir in Hokkaido was a case where GMs were applied to the reservoir in the cold region, and it was a main subject to clarify the temperature dependency of dynamic physical properties of GMs. B regulating reservoir in Aichi Pref. was a case where GMs were applied to the reservoir of high depth, and it was a main subject to evaluate the water-proof pressure of GMs to select thickness. C regulating reservoir in Okinawa Pref. was a reservoir located in the high temperature high humidity region, and it was a main subject to evaluate the influence which the site weather condition gave to dynamic stability of the site bonding parts of GMs. In addition, the durability evaluation of GMs was a common subject, and the deterioration characteristic of passing year of the real ageing of GMs was clarified by the sample collection from the test pond which had been used for 30 years.

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A large number of geosynthetics have been used to decrease environmental impact on waste disposal sites, and the geosynthetics have been of practical use to waste disposal sites. Although structure and maintenance of technical phase has been intensified useful technical information of geosynthetics is not so well known. The reasonable design method for geosynthetics is closely related with management and operation of waste disposal sites.
An inquiry was attempted to make clear the design and landfill management method concerning on lining system by 59 business organizations for design method and 65 waste disposal sites for landfill management. As a result, it is confirmed that a design method should be established taking account of analytical method of stress to lining system, material test method and related design criteria and estimation of material deterioration.

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