DMM (Deep Mixing Method) is an effective soil improvement method. In this study, the indoor test was practiced with a model apparatus of mixing machine and the mixing mechanism was considered to investigate the relationship between soil properties and the resisting moment, penetrating resistance on mixing blade of mixing machine. From this investigation, the method was proposed to estimate the kind and the properties of original ground soil.
The field test was practiced with actual DM-machine to ascertain the results of the indoor test. Moreover, two methods, the measurement of density and water contents with Radio-Isotope, and the work-done analysis, were proposed and verfied to appraise the quality of treated soil in field. From these results, the possibility for electro-mechanical control in DMM is considered.

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In situ orientation of the three planes of anisotropy in granite was at first investigated with the empirical aid of quarrymen at twenty-six quarries in the Inland Sea area in Western Japan. The azimuthal variation of the sound velocity was measured and the feature of the cracks was investigated on thin sections of the rock with an optical microscope. The defects were classified into open cracks, healed cracks and other defects for every rock. In the specimens from almost all of the quarries, the rift plane consists of open cracks within the quartz's grains and the strikes are nearly parallel to the horizontal plane. Thus the grain plane and the hardway plane is vertical. The grain plane consists of open cracks and/or healed ones within the quartz, while the hardway plane consists of a few cracks within the quartz but often consists of healed cracks within the feldspar grain.

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This paper presents a back analysis method for determining the complete three-dimensional initial state of stress and elastic constants of the ground, from a set of displacements measured during excavation of underground openings.
The method proposed here is formulated by the boundary element method, so that it can easily be applicable to three-dimensional problems, considering the sequence of steps for excavation, and the period for installation of measuring instruments in the back analysis.
In order to verify the applicability of the proposed method, computer simulations are carried out and the numerical stability of the method is demonstrated. The effects of scattering measurement data are also discussed in relation to the accuracy of the results.

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We examined the azimuthal distributions of circumferential strain, radial deformation, and V_p, V_s¶, and V_s⊥ of seismic waves traveling through a specimen of granite as it was deformed to faulting under the uniaxial conditions. All measurements were made within the plane perpendicular to the loading axis. It is concluded that anisotropy in physical properties of granite arises from the inherent microcrack fabric and anisotropic ordered alignment of microcracks extended or produced during loading (dilatancy-induced-fabric). Dilatancy anisotropy is much higher than anisotropy due to the natural fabric. The symmetry of physical properties can be characterized by the symmetry of dilatancy-induced-fabric. Based on the Neumann's principle in crystallography, we can simulate the mechanical behavior of granite with dilatancy-induced-fabric as an orthorhombic crystal.

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Seismic CT was employed to observe how dilatancy of rock localizes before faulting. The seismic CT can map the spatial distribution of P wave velocities. Since P wave velocity is determined by the extent of dilatancy (density, orientation, and aspect ratio of microcracks), mapping the seismic pofile is useful for observing nondestructively the progressive development of dilatancy. The specimen of Ohshima granite was compressed at a constant deformation rate under uniaxial stress. The reconstructions were made within the plane perpendicular to the loading axis. The maps clearly show the metamorphic changes of dilatancy before faulting; at first the formation of diffuse dilatancy occurred, the localization of dilatancy to a few near-surface areas followed at the next stage, and finally a failure zone appeared intersections of localized dilatant areas.

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Ultrasonic (seismic) computer tomography (CT) was applied to visualize water infiltration into dry granite and to characterize its presence. The ultrasonic waves carry the information of density, orientation, and aspect ratio of microcracks, and also the information of fluid within them. When the microcracks within a rock are filled with water, the effective bulk modulus of a rock increases, and hence V_p increases. In contrast, V_s is scarcely affected by the presence of fluid. Attention was focused on obtaining the spatial distribution of both V_p and V_s simultaneously. As expected, the V_s maps show no change, although the V_p maps clearly show large changes caused by the permeating water. It is possible to determine the presence of water within microcracks only by simultaneous reconstruction of V_p and V_s.

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In this paper, the method to identify the values of transmissivity and storage coefficient and those distribution in inhomogeneous aquifer is investigated in inverse problem. Especially, the importance of the selecting technique of observed head is emphasized, and the reasonable phases for observing is clearly shown with the sensitivity matrix. The applications of the proposed method to the simple aquifer model and to the area of the underground dam constructed are examined. Numerical values obtained agree well with the observed results in the field.

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The multi-column foundation has a broad applicability for under-water foundations. But it has a small rigidity to resist horizontal forces and rotation moments, consequently it yields large horizontal displacement easily. To reduce this horizontal displacement, the effect on the employment of diagonal column to the multi-column foundation is investigated by both the computations and the model experiments. This clarifies the characteristics of this foundation, i. e., diagonal columns are very effective against horizontal forces and the vertical reaction of columns varies depending on the thickness of the footing against vertical forces. Various methods to analyze the multi-column foundation are compared and it is found that the method of two-dimensional frame analysis is the most suitable for an ordinary multi-column foundation which supports symmetric loads. When three-dimensional problems are important, the finite element method which consists of shell elements and beam elements should be analyzed.

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In general, the peats classified into soft soils have the spongy fabric which is mainly composed of fibrous organic matters. These organic matters are partly decomposed plants such as leaves and stems. Therefore, the phase constitution and soil fabric of peat are quite distinct from those of inorganic soils which are made up mineral soil particles. Then, it has been said that the fibrous peat has very high compressibility and shows remarkable anisotropic shear properties. In this investigation, the samples of undisturbed fibrous peat were used. These samples contained organic matter in the amount of 70-80% by dry mass. Also, the three kinds of reconstituted samples of wooden chips with different shapes and sizes were prepared for tests. These samples were manufactured by supposing the fibrous peats samples. Both peat and chip specimens, in which ratio (H/D) of length (H) to diameter (D) is fixed at 2.5 and the diameters (D) are from 30mm to 100mm, were set in triaxial cell. After isotropic consolidation, the saturated specimens were sheared under drained and undrained conditions, respectively, and the influences of specimen size, shape and size of chips involved and difference of drainage condition on triaxial shear properties were investigated. It was found from test results that the specimen size, shape and size of organic matter involved and drainage condition strongly influenced the shear properties of peat and wooden chip specimens.

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Stress strain relations of rock masses are considerably different from that of intact rocks due to the presence of geological discontinuities such as joints and faults. In this paper, finite element analyses on these discontinuous materials are performed by using the elastic compliance tensor in terms of “Crack Tensor” proposed by Oda (1983) with the conclusion that the crack tensor approach provides a sound basis for approximating linear and non-linear elastic behaviour of rock masses. It has also become clear that input parameters for the finite element analyses can be determined by analyzing conventional tests on geological materials both in laboratory and in-situ.

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In order to investigate the compressive and shear characteristics of undisturbed Hiroshima type decomposed granite soils, the isotropic compression and triaxial compression tests were carried out using the undisturbed specimens made up by the new core bit. Test results were discussed paying attention to the degrees of weathering of samples.
The results obtained can be summaraized as follows.
1) The irreversible change of void ratio under isotropic compression is due to the particle breakage and the vanishing of structure effect.
2) The stress-strain behavior, stress-dilatancy relation and shear constant φ' depend on the degrees of weathering.
3) Failure criterion is expressed in terms of coefficient of the exponent.
4) The decrease in strength due to submergence is remarkable in a low confining pressure and in moderately weathered sample.

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The present paper briefly describes the theoretical aspect of the determination of stresses in rock medium which was established by one of the authors (Hirashima). The stress fields in an anisotropic elastic medium with a circular borehole are treated and the formulae to be used in practice to determine the stresses in an anisotropic rock from several measurements such as variations in borehole diameter, strains on the wall surface of boreholes and variations in axial direction of boreholes are presented. The results of calculation by Hirashima's theory and Amadei's theory, which has been published recently, are shown by a numerical example, and the differences between them are discussed.

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In order to investigate the mechanism of frost heaving in cohesive soil stratum, laboratory test was performed on cohesive soil.
The main concluding remarks derived from these studies are as follows; i) Having high water content and high saturation, specimens tend to display great amount of moisture migration and large frost heave, especially for small freezing rate. ii) Frost heaving process consists of primary and secondary processes. Furthermore, a simple calculation method of frost heave in laboratory test was proposed. iii) Although the soil sample was in the same state, a different pattern of frost heaving pressure was produced for a variation of void distribution in the specimen. This characteristic is closely connected with occurrence of ice lens.

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Normally consolidated clay layers with the undrained strength increasing with depth were successfully made with centrifugal consolidation. Loading tests were conducted on these layers using a rigid strip footing either with a rough or smooth base. The bearing capacities and deformations were measured and upper bound calculations were carried out. The observed bearing capacities are found to be smaller by about 20% for the smooth footing. The bearing capacities normalized by the strength at the surface increases with the increase in the parameter κB/c₀, where κ, B and c₀ denote the gradient of the increase in strength, footing width and the strength at the surface. The calculated upper bound of the bearing capacities and the failure mechanisms are in reasonable agreement with the observations.

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The distinct element method (DEM) have the potential applicability for analysis of fissured rock structures and granular materials. Before its practical application, a suitable procedure for determining material constants of elements should be developed. In the case of rock structures, the size of element is large enough to be made a specimen, and two procedures of determination of material constants K, η have been proposed by the authors. In the case of granular materials, however, the size of elements is too small to be tested individually. Mechanical properties of soil are used to be described in terms of the shear strength constants c, φ. It will be expected useful that the K, η can be determined with respect to the c, φ. In this paper, models of simple and direct shear test are analyzed by DEM, and the relationships among the K, η, the particle arrangement and the c, φ. are discussed.

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If the ground along an underground pipeline route consists of cohesionless soils likely to liquefy under the influence of seismic shocks, a pipeline buried in such soils may float to the surface of the ground water. In order to investigate the effectiveness of four types of stabilizing techniques of underground pipelines against liquefaction, we performed big size shaking table test. This paper gives a detailed explanation for the observed data and describes the effectiveness of stabilizing techniques.

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The triaxial compression tests along various stress paths were carried out in order to investigate the yield characteristics of dense sand in low and high pressure regions. The yield characteristics were discussed in particular reference to the pressure regions and stress paths. The results were summarized as follows: 1) The shapes of yield curves in low and high pressure regions are somewhat different each other, but they have very similar properties. 2) Based on the properties of the yield curves, a yield function is derived. The yield function was confirmed to have a comformability for the granular materials in a wide stress region. 3) The shape of yield curves can be determined approximately using the state parameter proposed by Moroto.

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Taking account of a combined singular stress state near a crack tip, we present a new hypothesis for determining fracture toughness criterion of rock-like materials under mixed mode I and mode II loading. The combined stress hypothesis gives a reasonable K_IIc/K_Ic which is in good agreement with published data on rock-like materials. Finally, the mixed mode fracture criterion derived by the hypothesis is tested by the measurement of K_I and K_II of flyash cement paste using the cracked disk specimens. The results are presented to confirm the use of this hypothesis for the problem of mixed mode fracture toughness including negative K_Ic.

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In order to investigate the mechanism of frost heaving phenomena in unsaturated cohesive soil, frost heaving tests were performed on unsaturated cohesive soil.
The main concluding remarks derived from these studies are as follows; i) A different pattern of frost heave curves was produced for a variation of water content and degree of saturation in the specimen. ii) The frost heave occurs as a result of the development of ice lenses formed by the water migration towards the freezing front from the unfrozen soil. The water migration is significantly influenced by the water content and degree of saturation in the specimen, iii) The frost heave characteristics have changed for the soil of the degree of saturation more than 85%.

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This paper presents the investigation on the characteristics of bulldozing resistance arising at the sides of track of a revoluting tracked vehicle obtained from the two-dimensional bulldozing resistance experiment with various types of soils and the revolutionary bulldozing experiment using blades.
It was revealed that the horizontal bulldozing resistance can be expressed in the function of two variables, the cutting depth and the amount of heaped soil, and the bulldozing resistance moment at the steering center holds a constant without relying on the turning radius. It was also clarified that the bulldozing resistance moment is estimated satisfactorily by use of the horizontal bulldozing resistance formula. Based on the experimental results, a predicting formula for computing the required driving force for the revolution has been proposed.

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A model introduced in the present paper is capable of describing cyclic behaviour of sand reasonably well. The salient feature of the proposed model is that a nonassociative relationship between stress and strain is used with the anisotropic hardening which undergoes a combination of isotropic and kinematic hardening. Generalized forms of Cambridge models are provided to represent yield function and plastic potential of sand. Translation rule of yield surface is specified by modifying Ziegler's kinematic hardening. The constitutive model is capable of accounting for expansion of yield surface with simultaneous translation. Several undrained cyclic tests for normally consolidated and over-consolidated sands are simulated by taking into account the membrane penetration. The effect of over-consolidation ratio on liquefaction is predicted and good comparison with experimental results is reported for the effective stress path and the stress-strain relationship.

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Construction standard in soil compaction was discussed on the base of the soil behaviour due to wetting that is considered to induce the most dangerous conditions of soil structures. The discussion was done by the following processes.
1) The suction that acts among soil particles was discussed with uniform spheres model to explain the difference of the compression behaviour and strength characteristics of partly-saturated soil from those of saturated soil. Based on this result, the volume change and strength reduction due to wetting was discussed.
2) On the result of 1), a method was suggested to estimate the volume change due to wetting, and was confirmed by one dimensional compression test.
3) The strength reduction due to wetting was predicted with the result of 1) and 2), and the direct shear test confirmed the possibility to predict the strength reduction.
From these investigations, the construction standard for field compaction was discussed considering the strength reduction and volume change due to wetting.

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In order to investigate the bearing capacity of a strip footing on soft clay with a surface crust and the deformations, a series of loading tests was performed. Model clay layers were made by combining consolidation on the lab floor with centrifuge consolidation. Based on observations in the experiments, an upper bound mechanism was proposed. As a result, it was found that the bearing capacity tends to increase with an increase in the strength of the crust and the deformations concentrate along the boundary between the crust and the underlying clay layer. It was also found that the proposed failure mechanism could give a reasonable prediction of the bearing capacity for this type of soils.

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Face stability is a particularly important factor that must be considered when tunneling in loosen sand layers. If face stability can be determined, it will be an important index for tunnel planning as well as safety.
The purpose of this report is to examine face stability in view of both the dynamic and physical properties of the ground and to stady standard judgements of face stability based on investigations, tests and measuring data collected from the Kokubu River Tunnel contract which was in a loosen sand layer in which the soil condition offered insufficient face stability.

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The finite element technique using the imaginary viscoplastic calculation scheme is employed to compute the perfect plasticity region such as failure state. And the calculation of bearing capacity of footing in anisotropic normally consolidated ground is performed by incorporating theoretical equation of anisotropic undrained shear strength into yield function. The influences of anisotropy of ground are analytically investigated with taking notice of stress distribution near and in the applied footing stress at collapse of ground.

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Direct shear tests were conducted on some kinds of undisturbed and compacted soils under unsoaked and soaked conditions to obtain the mobilized strength parameters, c, φ with shear displacement. The mobilized apparent cohesion obtained from the relation between normal stress σ and shear stress τ as a function of shear displacement strongly depends on the relation between shear stress and shear displacement. The strength anisotropy during the shear process is controlled by the anisotropy of cohesion during the same process. In the stability analysis of slopes, the safety factors as a function of shear displacement depend on the variations of strength parameters c, φ, the depth of slip plane and the inclination of slope. The overall calculation of the safety factor for actual design of slopes should consider the peak strength, and the maximum and minimum safety factors as proposed in this paper.

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