This paper describes the geotechnical properties of Ariake clay found in Saga plain, a lowland in north of Ariake sea in Kyushu, Japan. It is attempted to discuss the geotechnical properties of Ariake clay up to the depth of 20 meters by using the data of 110 exploratory boreholes drilled in different places of Saga plain. Simple regression equations are developed for some index properties and multiple regression equations are developed to estimate unconfined compression strength, compression index, compression ratio, and preconsolidation pressure from index properties. The efficiency of equations are discussed statistically by using the analysis of variances.

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In recent decades, the demand for underground space has been increased. Deep excavations are required to meet the demand, and, in many cases, excavation sites are in close proximity to existing structures. A major concern in these construction activities is to predict the lateral wall deflections and the ground surface settlements in the design stage. While numerical methods are often applied for the prediction of these movements, there are demerits because of the complexities of these methods, and it is desired to estimate the approximate deflections in a primary design stage. In this paper, a simplified procedure for the prediction of maximum lateral deflections of diaphragm walls is proposed, based on the research of empirical correlations concerning with factors affecting the behavior of walls in 52 case studies.

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Rock masses are fractured structure and consist of rock blocks in three-dimensional space: the nature and distribution of the fractures is termed “rock mass structure”. Although the 3-D geometry of the structure is one of the primary parameters that dominates rock mass behavior, the subject has not been studied adequately. This paper introduces a new computational 3-D geometry management method for rock mass structure, i. e., directed body theory. A computational system based on the directed body concept has been developed to the state where it can handle the terminated discontinuities in rock blocks and also non-convex blocks, together with calculation of quantities, such as volumes and surface area. Thus, the system fuccessfully produces a geometrical database of a representative 3-D rock mass structure in a generic manner.

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In case of construction of gravity structures in nearshore space, it is an important problem whether the structure slides or not during earthquakes owing to its buoyant force. This paper firstly describes the results of shaking table tests to investigate the sliding phenomena between the gravity structure model and mud stone during excitation. Secondly the characteristics of coefficients of static and dynamic friction at the contact surface between concrete and mud stone were studied using the direct shear testing apparatus. Furthermore, several numerical simulations of shaking table tests were performed by introducing the constitutive relation based on the experimental results.

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Two-dimensional nonlinear analysis method based on the effective stress is newly developed in order to predict a deformation of ground and structure during earthquakes. The governing equations derived from a two-phase mixture theory are firstly obtained and the finite element method is used for the spacial discretization of the equilibrium equations. Secondly, an elasto-plastic constitutive relations are introduced to describe the inelastic deformation behavior of granular materials under multi-directional cyclic loading conditions. Finally, the verifications of the proposed analysis method are performed through the several numerical simulations of model tests.

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The authors classified discontinuous planes existing in rock mass for two types which are non oriented small cracks and the oriented joint sets presented by Yoshinaka et al. (1990). The total deformation of rock mass is assumed by superposing the elastic deformation of intact rock, the opening of non oriented small cracks, slip and the opening of oriented jont sets. The yield mode of the rock mass is selected that the the stress conditions is satisfy on yield surfaces at first in the three types as intact rock, cracks and joint sets. The excavated rock cavern and rock slope models are analyzed and the applicability of the presented method is examined.

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The effects of shearing methods and specific areas on the cyclic undrained stress-strain behavior of sand were investigated by means of triaxial, torsional shear and direct shear tests using large scale specimens. It was found from test results that the liquefaction strength curves for specimens with different diameter almost coincide after making correction for the effect due to membrane penetration. But the liquefaction strength curves in direct shear tests decreases to some extent with the increase in stress ratio due to rocking of the cap. This phenomena become predominant in the direct shear test until the shear strain becomes around 3% in double amplitude.

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A series of model compaction tests have been carried out to investigate the effect of elimination of excess pore-water pressure during the vibrational compaction work. Consequently, the acceleration of ground during compaction, the penetration resistance of ground after compaction, and the sphere of compacted zone were cleared to be increased by eliminating excess pore-water pressure. And the rise of compaction effects was confirmed to be achieved by “intensifing the structure of sand particles”. Futhermore, the qualitative investigation about the earthquake resistance of compacted ground has been done by shaking table tests.

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This paper deals with a study of effects of initial degree of saturation and the initial dry density on the swelling characteristics of partially saturated silt during soaking. The observed effects of the initial degree of saturation and the initial dry density before soaking are discussed by a detailed look at the variations of the amount of swelling and the degree of saturation during soaking with elapsed time.

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The present paper describes the experimental results conducted to investigate some aspects of the wetting-induced collapse behaviour of compacted silty soil. Compacted soils wetted under load can both swell and collapse depending on their conditions (initial dry density, initial degree of saturation) and the magnitude of the effective overburden stress. For any given set of conditions, the amount of collapse increases with decreasing the initial degree of saturation, decreasing the initial dry density, and increasing effective overburden pressure. The practical significance of the results of the investigation are discussed briefly. The applicability of these results and conclusions to other soils will require further research.

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A series of field compaction tests have been carried out to investigate the effect of elimination of excess pore-water pressure during the vibrational compaction work. Consequently, the acceleration of ground during compaction, the blow counts (N-value) of ground after compaction, and the sphere of compacted zone were cleared to be increased by eliminating excess pore-water pressure. And the rise of compaction effects was confirmed to be achieved by “intensifing the structure of sand particles” by some field measurements of compacted ground. Futhermore, investigation about the earthquake resistance of compacted ground has been done by field re-vibration tests.

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In this paper, the mechanical behaviours of jointed rock mass have been characterized by a damage mechanics approach which is based on the hypothesis of complementary energy equivalence. Besides its computational simplicity, the main advantage of this approach when compared with other ones is that the Poisson's effects of rock mass defomation due to anisotropic damage can be taken into account. In order to demonstrate the applicability and effectiveness of the proposed approach, a finite element analysis of a cavern excavation have been carried out. It is found that the predicted response of the surrounding rock mass of the cavern using this approach is in good agreement with the observed data.

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The bearing capacity of reinforced foundation ground with one layer geogrid was formulated based on the upper bound theorem of plasticity theory. The failure mechanism of reinforced foundation ground was obtained using the results of model tests. Two reinforcing effects were considered in the proposed formula. The first is that the failure zone is extended, which is reflected by the enlarged angles of the rigid triangular wedge under the base of footing. The second one is that the shear resistance on the two lateral sides of the wedge increses. The calculated results were compared with the loading test results.

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The observational method has become common in geotechnical engineering practices such as tunnelling or underground excavations. The most important point for successful employment of the observational method is not only to evaluate results of field measurements as accurately and promptly as possible, but also to use the findings of the evaluation to re-design and monitor further construction procedures. Back analysis is a rational approach for quantitative interpretation of the results of field measurements. However, care has to be taken in selecting a material model to assure the uniqueness of the final results. In this paper, a method of back analysis is proposed, taking into consideration effects of non-elastic strains, and assuming that the stability of tunnels can be monitored by strain-based safety criterion. The method is simple. It does not require the pre-assumption of a material model, and it can account for the non-linear deformation associated with plasticity, creep, or that caused by blasting. The method was applied to interpret the data obtained from a umaxial compression test, a model test, and an actual tunnel under construction. The results show that the proposed analysis method could explain non-linear deformational behavior of a different nature.

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A model test of slope called “tilting box” is carried out on aluminium rod mass with various kinds of reinforcement, which is used as a two-dimensional model of granular materials. Based on the test results, the failure mechanism and effective reinforcement of slope composed of granular materials are considered. It became clear from the test results that the rolling of particles on the surface of slope is a “trigger” of the failure of the whole slope, the sliding like a rigid body along a slip line is not observed, and therefore the method of reinforcement to stop the motion of particles on the surface of slope is effective.

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The method proposed in this paper is able to perform economically the FEM analysis for the large-scale composite ground improved by sand piles. The method treats the stiffness of many pile lines as one of ‘a typical element’ by assuming some interpolate relationships between nodal displacements. As a result of analyzing the composite ground by the proposed method, it is clarified that ‘a typical element’ binding half of all pile lines shows reasonable output, that is, yield load on undrained condition and settlement during consolidation in the case of the ground whose lateral deformation is large. In the ground deformed one-dimensionally ‘a typical element’ can bind more pile lines to analyze within the allowed error. In such a case the proposed method is very efficient in terms of computing time and memoery capacity.

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Direct shear tests have been done to determine shearing properties of overconsolidated clays under consideration of microscopic view. The conditions of the clay are selected as follows. Kaolin clay is using as solid phase and conditions of liquid phase are selected for following three types, W-clay, Na-clay, and K-clay, The conditions of consolidation pressure are also selected five conditions. The microstructure of the clays are changed by these conditions. The degrees of the ped orientation are also changed. The results of the direct shear tests are shown different shearing characteristics that are selected different direction of ped (clay particle's orientation). The width of the shearing zone that the specimens with minus direction of ped are shown greater than plus conditions.

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Introduced is a procedure to achieve an optimum design of a building subjected to settlement taking the trade-off between the design of the super-structure and the design of sub-structure (foundation) into account. The super and sub-structure used to be designed separately in the current design method which seems not to be convenient in seeking the optimum design of the whole structure. The optimization procedure introduced in this paper is thought out to deal the design of a building subjected to differential settlement which requires both the super and sub-structures to be rigid enough to resist against differential settlement. The optimization procedure is adopted to an existing building constructed on a reclaimed land being on the process of primary consolidation. An economical comparison showed that the building designed in a current method was somewhat expensive than the building designed adopting the proposed tecnique of optimization.

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Slaking test are performed to examine the disintegration of soft rocks which easiely deteriorate by drying and wetting. For slaking test, some test methods, test conditions and evaluation methods of result are proposed. In this study. the Mizunami mudstones are used to slaking test and test results by another authors are analysed to investigate the methods for evaluate the disintegration of soft rocks. The results of this study are as follows: (1) settlement phenomina are confirmed by slaking of mudstone, (2) effective particle breakage indexes to evaluate a slaking of soft rocks are revealed, (3) a unique relation are recognized between two parameters (r. m) of a negative binomial distribution which correspond to grain size distribution after disintegration by slaking test.

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The aim of this paper is to investigate the pile end bearing capacity in highly breakable sands such as carbonate sand and decomposed granite soil, comparing with that in the hard grained silica sands, based on a series of triaxial compression and model pile tests, and further to discuss the estimating method of pile end bearing capacity in sands, considering the material compressibility. As a result, it was found that, even if much higher internal friction angle was obtained, the low pile end bearing capacity could be observed in the case of highly compressible sands. Further, a conventional manner to predict the end bearing capacity was presented empilically, combining the compressiblity to Prandtl's bearing factor for general shear failure.

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Based on the experimental fact that the test results of cemented sands under constant mean effective principal stresses (σ_m=const.) can be uniquely arranged on “Extended Spatially Mobilized Plane” (Extended SMP) which is modified from the original SMP by introducing “bonding stress σ₀” (=c·cot φ), an elasto-plastic model for frictional and cohesive materials is derived from “t_ij-sand model” for frictional materials by taking the effect of cohesion (σ₀) into consideration. The proposed model includes the Mises type model for metals (σ₀→∞) and the t_ij-sand model for granular materials (σ₀=0) at the both ends. It can predict the deformation characteristics of cemented sands under 3-D stress conditions. The overall good agreement between predictions and measurements indicates that the proposed model is able to predict the behaviour of frictional and cohesive materials under various kinds of 3-D stress paths.

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An adiabatic double lining in tunnel, in which a heat insulator was sandwiched between an outer lining and an inner one, was developed for a prevention work of icicles and frost heave of newly constructed tunnel. This paper proposes an approximate and reasonable estimation method of decreasing heat insulator depth, step by step, from portal to tunnel center according to an amplitude fluctuation of atmospheric temperature in tunnel. This also deals with temperature behabiours of a few adiabatic double linings in a long tunnel which was newly constructed, and the applicability of the proposed estimation method.

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Based on numerically simulated biaxial compression tests by DEM on granular assemblies with different interparticle friction angles or different initial fabrics, the microscopic mechanism of fabric changes and the correlaton between fabric changes and stress-strain behaviour of granular materials under shear is considered. And a general relationship between the shear strain on the mobilized plane and changes of interparticle contact angles which control fabric changes is made clear.

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To investigate the effects of hydrogen-ion concentration exponent (pH) on undrained shear behaviour of bentonites, consolidated undrained triaxial compression tests were performed on bentonites with different pH.
As a result, undrained shear strength increases with the decrease in pH and the maximum excess pore water pressure decreases with the decrease in pH. In addition, the diffusion characteristics (c_v-values and k-values) increase with the decrease in pH and it shows the bilinear relationship and the intersection point of two straight lines extrapolated from the initial and final portions of the curve is situated at the point of pH=7. The reason for this may be considered that different soil structures are developed with different pH.

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The flat dilatometer in situ testing device (DMT) is extremely simple to operate and maintain. The simplicity and low initial cost of the equipment is one of the main advantages of the flat dilatometer as an in-situ testing device. However, the simplicity of the equipment does generate some difficulty with the interpretation of the results. The discussion is concentrated on the soil classification using DMT in the present paper. Based on limited available test data, we investigate the reliability of the test results for classifying the soils from the DMT and propose a new soil classification using the DMT. A larger data base may enable a more definite soil classification to be established.

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In order to assess tunnel lining stability with a small number of covergence data, a simple method has been proposed here. Stresses, strains and displacements of the lining are back-analyzed from relative displacements measured at 3 points on inner boundaries of crown and side walls. Model test results showed high accuracy of the method. The method was applied to a practical tunnel and good applicability of the method was demonstrated by comparing the analytical results and the actual records.

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The conditions of K₀-consolidation and plane strain compression are most frequent in-situ stress conditions, such as in construction of embankment on natural deposit soft clay grounds. First of all, the development and advantages of a new designed t_riaxial apparatus for the conditions of K₀-consolidation and plane strain compression are presented. Secondly, the undrained shear strength properties of clay under the processes both primary and secondary compressions are discussed from the experimental results at any consolidation time. Some conclusions obtained from this paper indicate the points at issue in some previous methods for evaluating the increase in undrained shear strength of clay during consolidation.

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Since the uplift capacity of rock anchors depends upon the overall deformability and the strength of rock mass, the characterization of overall mechanical properties is very important. The authors have made in-situ pull-out tests of rock anchors and the characterization of rock masses at two geologically different sites. Rock types at the respective sites were sandstone and granite. In this article, the authors will first present the results obtained from various investigations for the characterization of rock mass. Then, they will present correlations among geometrical, geophysical and mechanical investigations and discuss their suitability for the characterization of rock masses for rock anchor foundations.

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A conventional method for compiling liquefaction hazard maps of large areas is proposed. A quantitative liquefaction hazard for a geomorphological land classification map in terms of the occurrence is built up byusing the Digital National Land Information and the location data of liquefaction in the historical earthquakes presented by Wakamatsu.
Predictions for the 1987 Chibaken Toho-Oki and the 1891 Nobi earthquakes are conducted based on the results of the analysis for several major earthquakes in Kanto and Tokai districts in Japan, and shows the good agreement with observations of liquefaction in the earthquakes.

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Sands deposited under water have been shown to be anisotropic. Their undrained response therefore depends on the direction of σ₁ (majro principal stress) in relation to the depositional direction. As a result the contractive behaviour has been observed in triaxial extension while on the other hand in compression the response is dilative at the same initial void ratio. This paper presents an analysis for the anisotropic undrained behaviour of sands under triaxial conditions. The following conclusions were reached.
(1) the proposed model successfully simulates the undrained behaviour of sands under both triaxial compression and extension.
(2) the cross section on the π plane of M (the stress ratio at the maximum volumetric contraction) has a major influence on the strength-deformation characterisitics of sand

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This paper describes the identification of the parameters of a groundwater flow model by the extended Kalman filter-FE. Water flow in an aquifer is used as the model of the unconfined flow. In the model, the infiltration into a subsurface, based on surface flow and rainfall, is taken into consideration. Parameters to be identified are permeabilities of the groundwater flow model and the infiltration into the subsurface. The analytical strategy shown herein is applied to both a hypothetical and an actual basin, and the numerical results are then discussed. After the identification of parameters, on the other hand, examined is the effect of construction sequence of an underground dam on the change of water level in the upstream. And a pumping rate at the wells from the underground basin is also determined to minimize the change of water level over the entire domain.

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A method for evaluating the undrained shear strength of clay during the processes both primary and secondary compressions is proposed from a consideration of one-dimensional consolidation models with creep. A new stress parameter is defined to evaluate the stress change during all processes of consolidation, which is called “conversion stress”. An equation for estimating the increase in the strength during consolidation is formulated based on the conversion stress. The validity of the proposed method is investigated from direct comparison of the calculated results with the experi mental ones. The calculated values are in satisfactory agreement with the experimental ones, which is obtained by some kinds of test with remolded and undisturbed clays.

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Face stability is one of most important factors to excavate safely a shallow tunnel by NATM in a sandy ground under water level. The results of a investigation aimed at evaluating the improvement effect of a sandy ground in tunnel improved by chemical grouting are prsented herein. In this investigation, the permeability test and the triaxial compression test in triaxial cell were used to detemined the permeability and the strength of undisturbed specimens obtained by the block sampling method from the improved sandy ground in tunnel face.
The results showed the followings.
(1) The grouting had sufficiently the effect to improve the strength and the waterproof of the sandy ground under water level.
(2) The laboratory tests of the undisturbed specimen gained by block sampling in this report were useful to evaluate the grouting effect.

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A hollow cylinder torsional shear apparatus together with its automatic control system have been developed in this study. The applicability and reliability of the apparatus are discussed using the results from stress controlled torsional drained tests and strain controlled torsional undrained tests for sand. It is shown that using the equipment softening behaviour in an undrained stress path can be investigated in detail for general stress conditions including consideration of changes of the principal stress direction.

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