FEM error due to discretization in the space domain causes inaccuracies in the nonlinear dynamic analysis of saturated soil, especially in the analysis of liquefaction considering large deformation. An adaptive strategy includes an error estimate and mesh refinement, in which the approximation is refined successively to a predetermined standard of accuracy, is essential to the effective use of finite element codes for practical analyses. In this paper, a posteriors error estimate procedure and h-adaptive FE are applied to liquefaction analysis of saturated soil using the elasto-plastic constitutive model and updated Lagrangian formulation. The advantage of this method is shown by the analysis of three numerical examples of saturated soil.

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The Micro-pile foundation, with small-diameter piles, may be used as a base of such slope works as rockfall countermeasures. The pile foundation of this type is often founded like on the debris deposit layer, which is not suitable as installation condition of pile foundation. Furthermore, excessive deformation of the base may occur, which is harmful to the foundation itself, for example, when big snow pressure will act to the structure. To mitigate such harmful alteration, the experimental research was carried out on mechanism of large deformation about small-diameter piles. This paper describes both the static model of a pile structure based on experimental results above mentioned and the relationship between a single micro-pile behavior and the load acting on the pile when the pile is constructed in such ground as debris layer

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During the past ten years, statnamic load tests have drawn attention from the piling community as one of the most economical methods for pile load tests. In this study, a small scale statnamic loading device was applied on model piled raft foundations in sand. On piled raft foundations, applicability of the unloading point method (UPM) which interprets the result of statnamic loading test was confirmed. Under statnamic loading, efficiency of pile group and load distribution ratio between the raft and the piles was investigated. As a result, the interpretation by the UPM gave acceptable results for piled raft foundations and it is possible to estimate the load distribution ratio from statnamic loading test on piled raft foundations.

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It is essential to take the effect of subgrade reaction into account for a good design of some structures. To this end, the accurate evaluation of coefficients of subgrade reaction is inevitable. Although design specifications provide empirical formulas for the coefficients of subgrade reaction, their accuracy does not seem to be adequate. Therefore, the improvement has been tried out by utilizing a horizontal loading test of a pile. However, this approach has not been explored much so far; in most cases only the trail-and-error procedure has been employed. In the present study, an inverse method for identifying the coefficients of subgrade reaction based on the horizontal loading test of a pile is proposed. Its validity is demonstrated by solving numerical examples. The accuracy and the way to improve accuracy are discussed as well. It turns out that the utilization of a pile of moderate stiffness and the computation using multiple test results under different loading levels at the same time can enhance the accuracy of the identification results due to the present inverse method.

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This paper describes the behaviours of suction foundations used for breakwaters during wave actions, mainly about pore water pressures and stresses in the foundation soil. The study has been conducted with the large hydro-geo flume which can generate waves of 3.5m and with a two dimensional finite element program based on the elastic theory, which can estimate the behaviours of pore water pressures and stresses in the foundation soil as well as super structure's displacements under wave action. The study has revealed that negative pore water pressure generates inside the suction foundation during wave action and contributes to the resistance of the breakwater against the wave action. And also the mechanism of the generation of the negative pore water pressure under horizontal loads is discussed.

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The barrier sheet is installed in the landfill to prevent for leachate to infiltrate into underground. The barrier sheet accepts drag-force by compacting work of disposed waste. However, a logical method to evaluate the tensile force creating at the anchored end of sheet has not been established until now. The authors present three methods, that is, (1) force equilibrium method considering earth pressure acting on vertical plane at toe of slope, (2) elastic method considering rigidity of barrier sheet, and (3) finite element method employing joint element between the components of the liner system. They also conducted centrifugal model tests of three layered liner system on the slope on landfill. In the tests, the thickness of barrier sheet is changed between 0.4mm and 2.0mm. It is found that finite element analysis gives tensile force creating at the anchored end of barrier sheet very close to experiments and elastic method gives the tensile force about two times larger than the experiments.

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It is one of the key issues to evaluate the effects of a conceptual model uncertainty and a parameter uncertainty of radionuclide transport on a safety assessment of a high-level nuclear waste disposal. In this paper, the inversion method based on the maximum likelihood concept was developed, and the values and the error variances (uncertainties) of radionuclide transport parameters were identified from a series of conservative and reactive tracer tests carried out in a single fracture at the Äspö Hard Rock Laboratory in Sweden. From the results, it is found that the parameter uncertainty caused by the model uncertainty is larger than that caused by the fluctuation of the observed breakthrough curve data.

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This paper describes shear strength, τ_v, characteristics in ultra soft clay grounds showing the decrease in water content, w, with depth. At first, it is confirmed that a strong τ_v-w relationship exists for given clay in each condition (consolidated condition and remolded condition). Based on this relationship, a reasonable method of determining τ_v-value at any point in w varying ground is obtained by use of the w-value at that point. Furthermore, a normalization of w by liquid limit is more effective for unique τ_v-w relationship irrespective of the difference in clay type compared with liquidity index in order to estimate shear strength.

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On railway embankments, slope coverage are usually constructed to protect rain-induced slope failures. Concrete block plate work which is one of the slope coverage has been used to take place of planting treatment, and the main object is considered to protect an erosion of slope. But except the object, the work posses an effect of restraint on rise of ground water level in the embankment during heavy rainfall. This paper deals with an influence of the slope coverage on the restraint of ground water in the railway embankments. First, we discuss results of rainfall seepage simulations on several model embankments tests and rainfall seepage/slope stability simulations on actual railway embankments. Second, we propose necessary length of slope coverage during rainfall.

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In order to predict the range of groundwater level fluctuation and the flow rate of spring water in a tunnel, which are caused by digging a mountain tunnel, some simple methods were proposed.
In this paper, the preconditions of these conventional simple methods are clarified. And new simple method, which can treat rainfall intensity and a coefficient of permeability that are not handled in these methods, is proposed by analyzing the results of a vertical-section-2-dimensional-finite-element-method. Moreover, based on results of new methods, the new method to set a range, which should be investigated and modeled for numerical analysis before excavation, is proposed.

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Recently, ground flow deformation mechanism considering pore water migration has been proposed. The mechanism is able to explain ground flow failure reasonably. However, there is a few study about the characteristic of soil that were injected pore water after cyclic shear histories. In this study, we injected the pore water to the specimen after giving the undrained cyclic shear stress using simple shear test. According to these experiments, it is shown that the characteristic of soil deformation after the cyclic shear history greatly depends on the magnitude of the shear strain during cyclic shear. And, it is shown that the soil skeleton is damaged by a positive dilatancy of opposite direction of initial shear stress.

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The minimum and the maximum density test for sandy-gravel is not standardized unlike for sand which is already standardized. In this research, a series of minimum density tests useing ten soil molds are performed as well as minimum and maximum density tests employing a 20cm inside diameter and a 20cm height mold and vibrating unit on sandy-gravel materials. The effects of testing details such as soil placement in the mold, soil surface cutting, how to density by a mechanical vibrator and the effect of particle gradations of tested materials are thoronghly investigated. Based on the results, how to standardize the minimum and maximum density test for sandy-gravels is proposed.

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This paper proposes a reliable method for back-calculating Mohr-Coulomb strength parameters c' and φ' from the measured displacements of subsoil under two-dimensional consolidation. The hyperbolic type of stress-strain model is employed to back-calculate c' and φ' before the subsoil reaches the failure state. The back-analysis problem is formulated as an optimization problem to find c' and φ' which minimize the difference between measured and calculated displacements. The method using incremental method and simplex method as non-linear stress-strain analysis and optimization technique, respectively, is effective for back-analysis of c' and φ'. The conditions to required back-calculate c' and φ' successfully are clarified.

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Magnetic resonance imaging (MRI) accepted as an imaging technique to produce high quality images for inside the human body in medical. MRI produces the three-dimensional volume images of the internal structures using powerful magnets and radio waves without any direct contact. This study attempted to apply the advanced images technique to observe the variation of water contents of clayey soils on drying. The distribution of water contents in the soil samples on drying was appeared using MRI.

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Utilization of coal ash as a geomaterial solves a solid waste problem and provides needed construction material. This paper presents the effect of cement additions on the unconfined compressive characteristics of compacted coal ash to promote coal ash recycling. The unconfined compressive strength of the samples drops off sharply on the wet side of optimum water content, whereas on the dry side, the unconfined compressive strength increases with increasing the water content. In addition increasing cement additions lead to increase in strength and stiffness. Several empirical relationships between unconfined compressive strength and curing time have been also developed The unconfined compressive strength of compacted coal ash containing cement at 96% of optimum water content increased more than those at all other water contents.

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Double torsion (DT) tests were carried out for Inada granite and Shirahama sandstone in water of between 1°C and 80°C. It was confirmed that the stress corrosion index decreased and crack velocity under the same stress intensity factor increased in the higher water temperatures. Activation energy from DT tests was compared with that from uniaxial compression tests, indirect tensile tests and CB (Chevron Bend) tests. Effect of water as well as thermal activation of stress corrosion was regarded as subcritical crack growth factors. Discussions on experimental results were made considering thermal stress analyses with FEM, fractal dimension of crack geometries and the DT tests results for glass specimens.

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