A second-order manifold method has been developed and is described. By means of a singular boundary element method proposed by the author, the failure process of a structure can be numerically analyzed. Mohr-Coulomb's law is employed as a criterion for new crack initiation and maximum circumferential stress theory is used as a criterion for the propagation of existing cracks. Comparison of the computed stress intensity factor with results obtained via the collocation method, demonstrates the high predictive accuracy of the present method. Examples of our present method applied to static and dynamic problems are presented.

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A pullout test model is proposed using hyperbolic relation for highly extensible soil-reinforcement. The non-linear equation for interface pullout mechanism was non-dimensionalised, expressed in finite difference form and solved numerically using the Guass-Siedel technique. A parametric study was carried out for various ranges of relative stiffness and relative bond resistance. The normalised load-displacement relations and the variations of pullout force and reinforcement displacements with distance, are presented. The interface pullout response of the model is compared with the available experimental pullout test results for geotextile, polymer and nylon geosynthetic reinforcements.

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This paper examines the validity of the Monte-Carlo simulation of fracture networks (MSFN) and the real-time inversion analysis (RTIA). The MSFN is applied to simulate the consolidation grouting and curtain grouting. Fairly good agreement with observed data is obtained for the relation between the pressure and amount of grout agents, 2) the spacial variation of Legion values, and 3) the appearance of grout agents in adjacent holes. The basic validity of the RTIA is verified through simple examples. Then, it is shown that the RTIA can predict the water channel conditions and the grouting distance for the consolidation grouting.

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A reliable grout analysis is important for the improvement of the grouting technology. Clarifying difficulties in developing such an analysis method, this paper proposes the Monte-Carlo simulation of fracture networks (MSFN) and the real-time inversion analysis (RTIA); the MSFN predicts the spatial variation of Legion values and the RTIA evaluates the water channel conditions and the grout agent flow. Input parameters of these analysis methods are geological data which are usually surveyed, and require no special measurement. The rigorous formulation of the MSFN and RTIA together with the explanation of a rock mass model to which the analysis method is applied.

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We had tried to estimate tunnel face stabilization about a new tunnel construction method using prelining and insert deck system. In this report, we carried out a large scale tank test for the purpose of confirming the phenomenon in the ground. As the result, we understood the three-dimensional ground diformation around the tunnel face, and the critical face supporting pressure for the stabilization. And also we confirmed that this method have an advantage in the face stabilization compared with conventional methods.

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Long-term measurements of ground movements were made at three different sections above an earth pressure balance shield tunnel driven through the Yurakucho lower clay, with special reference to influence of grouting for filling the tail void on settlements above the shield. The settlement data were separated into three periods, passage of the shield, tail void formation, and subsequent settlement. The results showed that the grouting significantly reduced the magnitude and rate of settlement during tail void formation, but had little influence on the rate of settlement during the subsequent settlement.

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The present study aims to clarify the mechanical behavior of a sand bed-structure system subjected to cyclic loadings such as wave forces. In order to simulate an element of ground beneath a structure in maritime field, a series of theoretical analysis and model tests were carried out. It was found that 1) the shear stress induced in the ground beneath a structure by wave forces changes with the depth and occurs at a perfectly reversal condition despite of the combinations of external forces, 2) the strength behavior of the ground obtained from the model test has similar tendency to that of cyclic triaxial test and 3) the directions of the external forces play an important role on evaluating the mechanical behavior of the sand bed.

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In order to clarify the mechanical behavior of a sand bed beneath a structure subjected to cyclic loadings such as wave forces, a series of model tests were performed under several loading conditions. It was found that 1) the failure of the ground beneath a structure on model tests becomes a progressive flow failure, 2) the formation of side walls on a model structure and the installing of sheet piles have advantageous as the countermeasure against the sand flow failure and 3) these prevention effects depend strongly on the structure shapes of side walls and location of sheet piles.

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This study developed a new method using buttress-wall type of ground improvement in order to reduce the wall deformation during large scale excavation work. The reduction concept of this system is explained with some effect. And centrifugal model tests have been used to clarify this concept, while in-situ monitoring has been also carried out to confirm the effectiveness of this system.
It was found that the reduction in lateral deformation of the retaining wall is closely related to the shape of buttress-wall type of ground improvement and also to the characteristics of the whole retaining system. We concluded that the expected improvement effect can be achived both at a improvement ratio of about 10 to 20% of imprved area, and at a narrow interval less than 7.5m between two rows of the buttress walls.

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Laboratory heating experiments were conducted to investigate the behavior of rocks under thermal stress. The experimental results indicated that the thermal failure behavior of rock greatly depended on rock types and confining conditions. Thermal stress analysis by the finite element method was carried out using the rock properties obtained from laboratory tests at high temperatures. The comparison between the results of this analysis and those of the experiments elucidated that it was essential in the analysis to consider the temperature dependence of rock properties, the thermal expansions in particular. This consideration allows the prediction of the location and time of fracture initiation caused by thermal stress.

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Undrained triaxial tests were performed on fine containing sands in order to investigate the effects of fine fraction on the liquefaction properties of sand. The results show that the liquefaction strength, which is determined by the double amplitude axial strain DA=5%, and the number of cycles Nc=20, takes the minimum value when the fine fraction is about 20%, if the relative density remains constant. This method, however, does not effectively evaluate the liquefaction strength of fine containing sand. Therefore, the authors investigated an alternative evaluation method using the limit excess pore water pressure ratio (Δu/σ'_c)_LT. The latter method is judged more effective for evaluating the liquefaction strength of fine containing soil than the conventional method.

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The lateral loading model tests of the tunnel lining are carried out in the sand-box in order to evaluate the interaction between the deformation of tunnel lining and the earth pressure acting upon it. Two models of the lining, steel or acryle pipe is used and two types of the test are performed. The one is the case that the active earth pressure is produced in the ground and the other is the passive earth pressure.
From the test, it is confirmed that the magnitude of the earth pressure directly acting upon the lining is changed according to the deformation of the lining itself. The pressure is evaluated by the analytical model in which the ground is the elastic springs setted over around the lining. Consequently, the interaction between the ground and tunnel lining can be explained by the introducing of the active ground spring constant and the passive one in response to the working realm, respectively.

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Large-scale model tests are conducted on geogrid-reinforced soil prepared with dense and loose Toyoura sand. The earth pressures and strains induced along the geogrids are measured during surcharge application and movement of the modelretaining wall. One test series are conducted with three geogrid sheets placed horizontally in the model. The other test series are conducted without geogrid reinforcement. The earth pressures are found to become smaller as the model wall moves away from the soil Especially, the earth pressures of the reinforced soil become smaller, compared with those of the non-reinforced soil. The strans along the geogrids also develop as the model wall moves away, and have peaks at the positions within 50cm from the retaining wall.
By comparing the earth pressure changes and the geogrid strains, the discussions are made with respect to the difference in the reinforcement mechanism associated with dense and loose soils.

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In order to investigate the dynamic behavior in the longitudinal direction of shield tunnel under transverse seismic force, a series of model shaking tests was carried out and the response analyses of shield tunnel were performed with emphasis on the seismic deformation method of time history. The investigation concerns the vibration characteristics of tunnel, the interaction effects between tunnel and ground, the analytical model of tunnel, etc. In the model tests, the irregular ground and different tunnel rigidities were focused, the ground and tunnel materials were chosen according to the law of similarity. An analytical model in the longitudinal direction of shield tunnel under transverse seismic force was proposed and validity of the model was verified by the model shaking tests. Response displacements of free ground in transverse direction were calculated with the 3-D FEM dynamic analysis and the multiple reflection response analysis, respectively.

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In order to investigate the dynamic behavior in the longitudinal direction of shield tunnel under the axial seismic force, a series of model shaking tests was carried out and the response analyses of shield tunnel were performed with emphasis on the seismic deformation method of time history. The investigation concerns the vibration characteristics of tunnel, the interaction effects between tunnel and ground, the suitability of the analytical model of tunnel under the axial seismic force, the effects on results of the response analyses of tunnel for using different calculation methods of the response displacements of free ground. In the model tests, the irregular ground and different tunnel rigidities were focused, the ground and tunnel materials were chosen according to the law of similarity. An analytical model in the longitudinal direction of shield tunnel under axial seismic force was proposed and validity of the model was verified by the model shaking tests.

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Unstable zones of underground caverns and rock slopes would be required to be monitored. Thus, a safe measuring method at distance has been necessary by eliminating to place devices or targets at the measuring points.
Here, a new monitoring method is introduced for underground chambers. The principle is that coordinates of a laser spot projected from one angle is calculated by using a triangle in a space formed by taking the image from the other angle. Then, many measuring points can be monitored by repeating the principle step by step. A test result concerning on the accuracy shows the capability in underground chambers. It is hoped that the study on the behaviors of rock mass failures would be propelled by using this method.

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A new parameter estimation methodology of determining unsaturated soil hydraulic properties from laboratory transient outflow experiments was investigated. In this method saturated hydraulic conductivity and unsaturated soil hydraulic properties in van Genuchten's equations are estimated by Genetic Algorithms incorporating finite element solution of Richards equation. Measured soil water pressure and cumulative outflow data as a function of time were used to evaluate the objective function. The utility of our proposed method is demonstrated using experimental data for Japanese decomposed granite soil. An excellent agreement between optimized and independently measured soil water retention data and saturated hydraulic conductivity were found.

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This paper discusses compression and rebound characteristics of two kinds of marine clays, based on the measurement of pore size distribution under one-dimensional compression and rebound processes by using a mercury intrusion porosimeter.
It is found that the characteristics of rebounding due to stress release and reloading processes are mainly associated with the macro pores and the mezzo pores of larger than 1μm of diameter. The normally consolidation processes are associated with the decrease of mezzo pores of which size are between 1μm and 10μm. High void ratio and high compressibility of Ariake clay are also discussed from a viewpoint of inter-aggregate cementation.

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This paper studies an importance of yielding characteristic and an effect of the microstructure on mechanical behavior of Osaka Upper-Most Pleistocene marine clay. Clay samples undertaken by the block-sampling technique are found to have higher quality than Pleistocene clay samples obtained by the tube-sampling technique. The following conclusions are obtained from the present study: 1. Yielding properties of Osaka Pleistocene marine clays from the two sites are anisotropic. 2. The Pleistocene marine clay has a linkage structure with significant bonding, which induces more brittle behavior, higher compressive strength and higher stiffness than the disturbed and reconstituted samples.

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The appropriate modeling of mechanical behavior of a discontinuity and the quantitative determination of its characteristics have an important role on evaluating the stability and deformational behavior of structures in the discontinuous rock masses. This paper is to present the laboratory test techniques and a rational procedure for the determination of deformational characters and strength of natural rock joints. The problems concerning with the assessment of these characteristics in the previous analysis are also pointed out based on the investigation of the shear tests conducted on several types of real natural joints. The distinct element analyses, in which both liner shear stiffness and non-linear one are introduced for the same ground conditions, are also carried out to clarify the effect of non-linearity of shear stiffness on the deformational behavior of rock structures.

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Before construction of any structures on surface or subsurface of alluvial clay layer, the cement mixing method is used frequently to construct a thin improved layer at certain depth of ground. However, the confirmation of improved layer is performed by only boring and laboratory testing. In the present paper, the confirmation method using s-wave reflection method, and the simulation analysis which as certain continuity of an improved thin layer is proposed. Especially in this analysis, the proposed method for the model at a thin layer of high velocity which lies between two layers of low velocity is examined, and the results of this simulation analysis are found to be applicable construction site.

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A 3-hinge arch precast structure which consists of an arch element produced in factory was developed as an arch structure instead of short-span bridge or cast-in-place culvert. Recently, this method was adopted in Japan, but in a seismically active area like Japan, it is necessary to study the a seismic characteristics of this structure.
In this research, shaking table tests were carried out to examine the effects of the density of foundation and the effects of intensity of shaking on the dynamic stresses induced in the 3-hinge arch and on the displacement of Terre Armee wall. In addition, a comparison between the experimental results and the analytical results obtained using existing two-dimensional seismic response analysis was performed.

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The Statnamic load test is a kind of rapid load test and its loading duration is within about 200ms. This test has several advantages such that no reaction beams and no reaction piles are required, and that time for testing is very short compared to the static load test without a delay in pile construction work. However, the Statnamic load test results include dynamic effects such as inertial effect and penetration rate effect. When we use the Statnamic load test instead of the static load test, it is necessary to remove dynamic effects from the test results. This paper studies the interpretation methods of the Statnamic load test results, and systematizes their applicability in practice.

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At the completion of a regulating pond in the land developed for an industrial complex, the water near the bed of the pond was found to be highly acidic. As a result of investigations, it was found that high acidity was attributable to the formation of sulphuric ion due to pyrite (FeS₂) contained in the mudstone layer (sedimentary mudstone layer in the Neogene period) exposed on the bed. In order to correct the situation, the costruction of a cover on the bed was proposed. The VE method was used for selecting a countermeasure. A method was finally selected to remove the soil surface which had turned acidic, and then costruct in its place a cover of improved soil, which is a mixture of the quality soil produced in the site and soil stabilizer. The validity of the countermeasure was verified through pilot construction, and the specification for implementation was determined based on the data obtained. The regulating pond was filled after the implementation of the countermeasure. It was confirmed that the pH of water started to stabilize in more than five months and gradually became close to 7.

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