A method of back analysis for estimation of material properties and initial stresses of rock mass is represented by the exact elastic solutions. These exact solutions due to the present analysis give the displacements and stresses of a circular or an elliptical tunnel of an anisotropic (or an isotropic) medium, under two-dimensional in-plane loading conditions. The practical availabilities of this back analysis are shown by several graphical representations and by the numerical results applied to some field measurements.

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The cyclic direct-simple shear tests on undisturbed Drammen clay were carried out. Every test involves several series of consequtive undrained cyclic loading with drainage between each series of cyclic loading. The results from laboratory tests indicate the followings: (1) For normally consolidated clays, cyclic loading followed by drainage will be beneficial to resist the subsequent cyclic loading. On the contrary, for overconsolidated clays cyclic loading followed by drainage may be unfavourable and lead to larger cyclic displacements and a small number of cycles to failure during subsequent cyclic loading. (2) The recompression index obtained from conventional oedometer tests can be adopted for predicting the approximate values of post-cyclic recompression settlements. (3) Drainage after undrained cyclic loading improves the undrained static strength.

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In this paper, we discuss a back-analysis method for determining the two-dimensional in-plane initial state of stresses and elastic constants of the ground, from a set of displacements measured during progressive excavations of underground tunnel.
The proposed method of solutions bases on the exact elastic theory by using of complex variable method with a conformal mapping transformation, which can be treated for an arbitrary shape of the tunnel.
The results of stresses, strains and displacements at arbitrary locations in rock ground are exactly computed by the given values of in-plane load, elastic constants and shape of the tunnel.
In order to verify the practical availavilities of this back-analysis, several numerical results are given in relation to the accuracy of the results.

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The precompaction pressure and strength of compacted soil-gravel mixture are estimated from the density and the water content of the mixture provided the following two types of experiments were carried out prior to the compaction work in the field.
(i) The soil portion of the soil-gravel mixture were compacted and sheared under constant volume conditions. This test should be carried out on the soil with several different values of water content. Thus, the dry density-compaction pressure curves during compaction are obtained with the water content of the soil as a parameter. The constant volume shear strength is also related to the compaction pressure.
(ii) The specific gravity and the water absorption tests were carried out on thegravel portion of the mixture.
Based on these tests, the density and the water content of a soil-gravel mixture are converted to the density and the water content of the soil portion of the mixture using the correction method proposed by Walker and Holtz.
A series of large-scaled triaxial tests were carried out on compacted soil-gravel mixtures to ensure the performance of the procedure proposed in the paper. The test resuits were found to be in accordance with the precompaction pressure and strength estimated by employing the proposed method.

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An adiabatic icicle prevention work has been provided in many tunnels in cold climate where icicles and side-ices grow. This paper deals with an approximate estimation of narrowing amplitudes of atmospheric temperature and depth of heat insulator in a tunnel with an adiabatic icicle prevention work. A fluctuation model of a cyclic atmospheric temperature change in a tunnel is in an approximation combined with a nonsteady state heat convection/conduction model including heat insulator, tunnel lining and ground. Thus even if an adiabatic icicle prevention work is provided over all the length of tunnel, the atomospheric temperature fluctuation can be reasonably estimated and the heat insulator depth can be economically decreased.

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This paper describes a probabilistic evaluation method of pile capacity, in which the ultimate axial capacity of single pile is predicted effectively based on the information both of an in-situ pile test and statistical data, with Baysian probabililty theory. In the probabilistic model, a cohesion factor at the toe of pile, adhesion factors between pile surface and soil and averaged N-values of soil layers are assumed as random variables. Applicability of the proposed method is verified using experimental data in two different sites, in which load capacities of 2-3 single-piles are tested separately. Pile capacities are calculated by those factors, whose means are determined by experimental data, as if obtained by a single test. The calculated capacities among self-prdedicted a nd others are almost the same values.

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The materials for gravel drain piles are required properties for possesing both high permeability itself and a resistance to clogging due to fine grain filtration for the surrounding ground. However these requirements are inconsistent with each other. Two states of no-clogging criterion can be considerd: one is the state that no particle of surrounding ground goes into the drain pile. The other is the state that some particle goes into drain pile and forms a stable filter zone which keeps the constant condition for permanence. The latter has higher permeability and is more suitable for countermeasure against liquefaction. This paper presents short term clogging test and moreover suggests a new criterion for no clogging of drain material based on the results of the above experiment.

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In this paper, a numerical method named FLEM (FLow Element Method) will be described. The authors have developed the method to analyze large deformation and flow problems in geomechanics. The processes of making a element stiffness matrix and calculating nodal forces are the same to FEM (a global stiffness matrix is not formed). Each node has a virtual mass representing the mass of the surrounding elements, and under unbalanced nodal forces each node displaces along a direction of nodal force vector according to the equation of motion. FLEM adopts the explicit time-marching solution scheme in solving the equation of motion. This process is the same to DEM, so it may be said that FLEM is a practical method coupling DEM with FEM necessarily. It should be emphasized that FLEM analysis does not need large matrix computations and complex lagrangian coordinate expressions.

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Blocks of undisturbed sample of scoria were procured from the construction site of a pneumatic caisson. A series of triaxial, plane strain compression tests was carried out for the scoria both in undisturbed and disturbed states. The results showed that (1) the undisturbed scoria is highly compacted with a relative density of more than 100%, and an apparent cohesion of about 100kPa, (2) the behaviour of the scoria changes from that of a dilatant brittle material to that of a plastic material in the confining pressure range of 700 to 1500kPa, exhibiting volume reduction with particle crushing, (3) the difference in behaviour between triaxial and plane strain compression tests gradually diminishes with an increase in confining stress, (4) the cohesion term mobilizes to the full at the axial strain of 2% and is destroyed at about 8% of the axial strain.

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This paper deals with the experimental and analytical evaluation of segment ring of shield tunnel considering the change of clearance of tail-void during construction. The experimental investigation consists of large-scale model tests which can satisfy simillarity rule. Further, the application of back analysis for the calculation of external pressure on the segment ring from the strain data is described. The analytial investigation consists of FEM analysis by using GAP element which can simulate the clearance of tail-void. These experiments and analyses proved the appropriateness of the design method of planning real segment ring in Trans-Tokyo Bay Highway Project.

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Concrete U-trough used as road gutter is often damaged by frost heaving pressure during the winter season. In this study, 450 milimeter ready made concrete U-trough specified in JISA 5305 were experimentally set under the following conditions. 1) backfilled with in situ soil (no countermeasure). 2) backfilled with gravel having thickness of 15, 30, 40 50 centimeter. The frost heaving pressure, deformation, and so on arise at these troughs were measured. The main results of these field tests were as follows.
1) The effect of gravel backfill for reducing frost heaving pressure was evidentry recognized.
2) In the tested condotions used in this study, there existed a backfill thickness at which the frost heaving pressure acting on the side wall of trough had a minimum value.
3) Under the certain conditions, the optimum thickness of gravel backfill for reducing frost heaving pressure could be determined reasonably.

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