An evaluation method of hydraulic properties was proposed in an area of rock masses from meters to tens of meters. Hydraulic conductivity and porosity between pressurized and observed point in several boreholes were determined by inverse analysis of pressure changes at observed point using pressure changes at pressurized point. This new method has two features; 1) hydraulic parameters can be estimated using analytical solution of pressure diffusion with variable flowrate, and 2) variety pressure changes of pressurized point are acceptable because they are treated as discrete data. Hydraulic properties around underground rock cavern evaluated by an application of this method to field data were largely consistent with results of in-situ tests.

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Recently, a large number of waste landfills become to be full because the amount of waste increases. It is difficult to utilize these waste landfills because of it's low strength and heavy metals included in it.
In this paper, a method for ground improvement of in-situ waste landfill by heating in the ground without cement addition or compaction is suggested. The increase of foundation strength and the decrease of release of heavy metals have been achieved by this suggested method, in-situ heating of ground by the hardening process of hydrate which is formed into chemical reaction of water and Calcium Oxide. The validity and the feasibility of this method are verified by the series of laboratory test.

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We studied the influence of size and position of assumed slip line and definition of limit state on estimated stability of a slope during an earthquake, performing search of critical slip lines and probabilistic safety assessment. The critical slip line is searched based on 2-dimensional dynamic analysis by Genetic Algorithm, in which not safety factor but limit acceleration is used as the objective function, because the critical slip line depends on the amplitude of input motion. The limit acceleration is defined as minimum peak acceleration of input motion that causes the failure event. The limit sate is defined for both case, balance of slip force and resistance force, and slip displacement. It is indicated in numerical examples that cohesion of residual strength has large influence on position and size of critical slip line, but those of the slip line is not so sensitive to failure probability.

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A high level radioactive waste disposal facility may be built on a coastal area. Therefore, it is important to investigate the influence of seawater on bentonite buffer material. The purpose of this study is to investigate the influence of seawater on the swelling pressure and swelling deformation characteristics of five typical kinds of bentonites. This experimental work clarified the relations between the influence grade of seawater and compaction density, type of exchangeable-cation, montmorillonite content of the bentonite, and vertical pressure condition. Based on experimental results, a specification for the buffer material which can overcome the influence of seawater was defined.

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This study is intended to describe the influence of the initial static shear stress on post-cyclic deformation characteristics in triaxial compression and extension tests on Toyoura sand that underwent pre-consolidation under isotropic and anisotropic consolidation stress states in the compression and extension domains. This study specifically addressed the effects of principal stress direction and principal stress reversal, which were developed during post-cyclic monotonic undrained shear when the cyclic load was given to the specimen. Results revealed that both the stress reversal and stress direction during compression and extension shear produced a marked degradation in deformation modulus as well as undrained strength.

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A new method is proposed for predicting an increase in shear strength of soft ground due to embankment construction. A proposed formula for this prediction was derived on the basis of the concept of critical state line in logƒ-logp plane. Only two parameters were used in the formula: the slope of logƒ-logp curve of the soil and compression strain of the soil stratum. This formula can be applicable for both normally consolidated soils and over consolidated soils including peat soils. Verification of the method showed good agreement between predicted shear strength and measured one.

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The design of earth structures has been transformed from the deterministic design method with safety factors to the limit state design with load and resistance factors. Reliability analysis was applied to reinforced soil retaining walls with various heights for sliding and overtunirng mode. An allowable reliability index and reliability-based load and resistance factors were presented in accordance with the conventional safety factors with various averages and coefficients of variation of soil unit weight and friction angle and tensile strength of reinforcement. As a result, the averages of load and resistance factors were independent of wall heights and soil category, while they were dependent on the failure mode.

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In this study, measurements were carried out on thermal conductivity of granular replacement materials to be possibly used for a countermeasure against frost heaving of structures. As the replacement materials, various granular wastes were selected as experimental samples for an aim of effective utilization of wastes. For comparison, the coarse material of crushed rock, which used generally as replacement material, was also measured for their thermal conductivities by using non-stationary thermal probe method.
In this paper, we clarified the relations between thermal conductivities and their influence factors, such as, particle size of samples, dry density, moisture content, temperature conditions etc.

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Triaxial compression and extension tests were carried out on unsaturated Toyoura sand specimen under constant confining net stress and suction. The obtained data were exaimined, and compared with the observed behavior in triaxial test of unsaturated clay specimen. The similar effects of suction for the clay specimen were confirmed for the trixial compression test results, but not for the triaxial extension test results. From the discussion of the micro scale mechanism concerning to the soil water distribution, it is deduced that the effect of deformation mode has influence on these observed behaviors.

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The seismic coefficient method used for an earthquake-proof design method of gravity retaining wall is not clear to be actually the safety side method. Because it covers the unknown field of phenomenon by various safety side setups but it also contains dangerous side setups. Then, it is necessary to make clear the seismic behavior of the gravity retaining wall and take it into the design to make the design method be rational. So conducted centrifugal model tests of gravity retaining wall. Data analysis showed that the present design method is able to be rationalized by calculating the seismic earth pressure by the active earth pressure of static state, setting the seismic coefficient to be 0.4, etc.

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A series of undrained shear triaxial tests were performed in this study on sandy-gravel materials with different fines content and different relative density. According to the undrainened cyclic and monotonic loading triaxial tests, liquefaction strength and maximum deviatoric strength considerably reduce as the fine content increases from 0% to 10% having the same relative density. It clarified in this research that, when non-plastic fines are mixed in sandy-gravel, undrained shear characteristics in cyclic loading and monotonic loading for virgin or post-liquefaction soils largely change. Hence, it is important to evaluate the influence of fines fraction on the undrained strength properties appropriately.

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