In this paper, dynamic analyses on a full system, which consists of ground, group-pile foundation and superstructure, are conducted using a three-dimensional static and dynamic finite element analysis code DGPILE-3D to investigate the seismic performance of a steel-pile foundation with inclined piles. And dynamic analyses, in which an axial-force dependent model for pile is introduced, are conducted to evaluate the behavior of inclined piles filled with concrete. Furthermore, the seismic performance of a steel-pile foundation with inclined piles is evaluated in comparison with the caisson foundation, which has the same magnitude as the steel-pile foundation, and then it was found that the seismic performances of their foundations for the superstructure are nearly same.

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Due to the technical difficulties, an analysis has been made only on two-dimensional planes in the design of a sealing structure. As a result, no verification has been made on the seismic performance at the corners of bulkheads. With a parallel computation method, it models sealing sheet piles and bulkheads meeting at right angle simultaneously, and to identify the behavior of corners of bulkheads and the stress state occurred on the sealing sheet piles when subjected to the level II earthquake. This study showed the inplane shear stress of the sealing sheet piles at the corner areas being at the most critical state, as well as the sealing performance of the sheet piles.

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This paper discusses the volume change characteristics of compacted soil based on the oedmeter test results. Each of the specimens was made under different water content, different compaction loads and different methods representing static and dynamic compaction, and the compression tests were conducted in soaked condition and unsaturated condition. The effect of the conditions of compaction for the compression curve is discussed.
The evaluation method for deformation characteristic of compacted soil is discussed and the constitutive model for the compacted soil is proposed. Using the derived equations, the oedmeter test results were simulated. The calculation results simulate the compression curve of compacted soil well, by using the parameters of suction, water content and yield stress.

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Castle masonry walls in Japan have various cross-sectional shapes. Each individual masonry wall has different height, gradients, curvatures, processing conditions, etc.. Considering some factors to be related to these masonry shapes, an advance was made in technique of masonry walls construction. As the result, it becomes clear that the stability of the masonry wall stones is greatly influenced by their gradients and curvatures.

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The purpose of this paper is to improve technologies of the grouting for excavation disturbed zone in order to recover low permeable rock masses for research and development on geological disposal of high-level radioactive waste. In this study, experiments of grouting injection test are performed on bentonite slurry mixes with saline and ethanol in the laboratory. From the results of the tests, low viscous and high density bentonite slurry is found to be able to inject the concentrated bentonite slurry and to recover low permeable in the fine fractured aperture. In conclusion this bentonite slurry is able to be expected the grouting effects for excavation disturbed zone in order to recover low permeable rock masses.

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Frost heave tests under the triaxial stress condition are performed to study the influence of several factors on the frost heave ratios in triaxial directions. The effective stress increase under small confined stress due to the decrease of pore water pressure during freezing makes the frost heave ratios smaller in both the heat flow and its perpendicular directions. The earth pressure increase in the heat flow direction makes the frost heave ratio smaller in the heat flow direction while larger in the perpendicular direction. Because of consolidation in unfrozen soil, the frost heave ratio in the heat flow direction of soft soil is smaller than that of hard soil. The numerical model of the frost heave ratios considering these factors as well as the traditional experimental formula of triaxial frost heave, is proposed. The validity of the model is confirmed by comparing the analytical values with experimental results of the frost heave ratios.

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There are many labor accidents in which workers or operators are buried under collapsed earth, or are injured when construction machinery such as a drag-shovel falls or topples over the edge of the trench during excavation. Our survey on labor accidents revealed that about 30 workers die every year in this type of accident. This study examined the stability of the trench excavation sites under the construction machinery load by the following procedures : 1) The load of construction machinery was modeled; 2) Failure behavior and depth of excavation were studied by conducting centrifuge model tests using an in-flight excavator, with the test parameters such as the magnitude of the machinery load, position of the load, etc.; and 3) The results from the upper bound solution based on the observed failure mechanism were compared with the failure mode in the centrifuge tests, and a good agreement was found.

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In the case of construction of repository for nuclear waste near the coastal area, the effect of seawater on swelling characteristics of bentonite as an engineering barrier should be considered. Effects of high-temperature history on swelling characteristics of bentonite should also be considered because nuclear waste generates heat. Thus, in this study, swelling characteristics of bentonite on the conditions of high temperature history and swawater are investigated. The results of this study imply that : (1) Swelling strain of sodium bentonite or transformed sodium bentonite decrease as the salinity of water increases, whereas those of calcium bentonite are not affected by salinity of the water. (2) Quantitative evaluation method for swelling strain and swelling pressure of several kinds of bentonites under brine is proposed. (3) Using distilled water, swelling strain and swelling pressure of sodium bentonite with high-temperature history is less than those without high-temperature history.

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To study effect of particle crushability on behavior of coarse material, compression test and biaxial test were simulated by the Distinct Element Method considering particle crushability. Particle crush was observed uniformly at everywhere inside the specimen, and where it occurs, the interglanular force reduces. This result shows that particle crash is not the predominant but the secondary cause for the change of the particle structure. It was also confirmed that the critical state line for the particle of the intermediate crushability exists between those of particles of the high and the low crushability. This result means that the effect of crushability of particle is explained with change of the critical state line.

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Mechanism of generating lateral earth pressures on the retaining wall has not been clarified yet as these pressures are influenced by many factors such as deflections of the wall and the properties of soils. So an in-flight movable earth support equipment for the centrifuge test has been newly developed to carry out a series of tests to observe the redistribution of the earth pressures during the deflection of the wall. The results show that the earth pressures as well as the deformation of the backfill are strongly influenced by the position of wall and the process of the wall deflection.

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Recently, centrifuge model testing has been adopted on many liquefaction geotechnical subjects. However, the saturation degree of a sandy ground with viscosity fluid was hardly investigated, and the effectiveness of the testing on simulating liquefaction is not clarified yet. In this study, the saturation degree of the sandy grounds was investigated in gravitational and centrifugal field. The modeling of models test was also carried out to demonstrate the effectiveness of a centrifuge model test. In the result, the preparation technique had no small effect on the saturation degree. The effectiveness of a centrifuge model test was confirmed on the characteristics of response acceleration and pore water pressure.

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More than 50 undisturbed and remoulded clayey soil specimens were tested using hollow cylindrical torsional testing apparatus. The marine clay was sampled from 5 different harbours and coastal locations in western Japan. Sand and clay were mixed in various proportions for testing. The plasticity index of the sampled soils varied from 16 to 111 and the particle distribution curves were also variable. Based on experimental results, a unified formula representing the dynamic shear moduli and damping ratios for the clayey soils with various plasticity and sand contents is presented.

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