Considering the ground-bolts interaction in the rational design of tunnel support using the New Austrian Tunnelling Method (NATM), the mechanical behavior of the grouted rock bolts and supporting effect on tunnel stability was analyzed. A new elasto-plastic analysis solution was obtained, in which the shear stress due to the cohesive action between the rock bolts and ground owing is modeled to the effect of the rock bolts, the strain softening and dilatancy behavior of the rock after it yielded was taken into consideration. By a detailed parametric study with the newly proposed analytical theory, a method for the optimum bolt length and support pattern was found which effectively controls the tunnel convergence and the size of the plastic zone arround the tunnel.

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The authors propose the slope stability analysis method using the springs attached to the interslice plains based on the limit equilibrium method and discuss the application results. In this method (SSM), the slope is assumed to be a set composed of the rigid slices, elastic springs, and plastic sliders. The interslice forces are determined logically by the deformation of the vertical slices which are gotten from the stress-strain relation of the soil. The unique result of overall safety factor, a set of interslice forces, etc. are analyzed by using of this method. From the analytical results of the model slopes using the proposed method, it is clear that the safety factor, interstice forces, etc. agree approximately with the results of the Rigid Body Spring Method.

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Since the planning and design stage of the construction of closely running four shield tunnels proposed in Kyoto city, authors have been engaged both in the study about various problems in the parallel shields and in the construction works with close monitoring by computerized construction systems for priority works, aiming for contributing to the influence evaluation of the ground-tunnels behavior in parallel shield tunnels in future.
The paper describes the evaluation and application of the followings; 1. the influence load to the preceding shield by the driving force of following shields, 2. characteristics in load changes in the long term effect of the parallel shields and 3. analytical illustration techniques about the ground behavior mechanism.

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This paper presents the cokriging procedure used to estimate the pile tip level. Correlation of spatial variables with the ground surface level are taken into account. Cokriging is a geostatistical method to estimate spatial distribution using two or more correlated random variables simultaneously.
Accurate estimates of pile tip levels are very important in the design of piled structures. The purpose of this paper is to describe a reasonable stochastic model and estimating methods using maximum likelihood estimation. The model and methods are applied and verified using actual data of the pile tip levels. It was found that cokriging is available for estimates of pile tip levels which are correlated ground surface levels.

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Dynamic loading tests are carried out for test specimens of hard rock blocks with cracks. Stress-strain relations at low strain levels are observed and their deformation characteristics are studied. Wave velocities evaluated from dynamic loading tests are compared with those due to resonance method and ultrasonic method. There are some differences among these wave velocities and their relations varies according to the density of cracks in the specimens of hard rock blocks. Strain rate dependency of wave velocity and the effect of the distance between cracks and routes of wave propagation on wave velocity are investigated.

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In chemical grouting, it is difficult to evaluate the improved region. To solve this problem, we proposed the evaluation method of improved region by resistivity tomography. In this study, the applicability of this method was investigated by a series of model tests in the laboratory from the viewpoints of the electrode arrangement and the resistivity contrast between grout and ground water. The test results showed that the evaluation was accurate if the electrodes and solidified region were close to each other. The electrodes must therefore be placed at the adjacent points to the grouting region designed. Furthermore, the test results showed that the improved region was evaluated accurately when the resistivity of the grout was less than one-tenth of the resistivity of the ground water.

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It is well known that soft rocks are disintegrated by repetitions of drying and wetting, and the embankment using soft rocks sink due to submergence for a fairly long period. However the relationship between the degree of disintegration and settlement behavior of such soft rock is not clarified sufficiently. Then, the purpose of the present investigation is to make it clear the relation of settlement behavior of specimen, physical properties and disintegration properties of soft rock. In this study, it became clear that the relationships between some particle breakage indexes, liquid limit, plastic limit, content of montmorillonite and settlement behavior.

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The moduli of deformation of the remolded Shimajiri clay are experimentally investigated in the present paper. These moduli consist of modulus of elasto-plasticity and coefficient of viscosity in terms of effective stress. Generalized Voigt model is applied to the deformation of elasticity and viscosity, and modified Cam clay model is applied to the deformation of plasticity. A new test method is proposed to determine the coefficient of viscosity of clay in terms of effective stress. The experimental results were compared with the estimated results, and the applicability was verified.

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The authors had proposed the back analysis method for the estimation of earth pressure or coefficient of subgrade reaction in excavation work, using the extended Kalman filter of control theory. In case of simultaneous estimation of earth pressure and coefficient of subgrade reaction, this procedure is unstable.
This paper describes the new back analysis considering moment of retaining wall and the external forces as the observation vector for the observation equation. Using this method, earth pressure and coefficient of subgrade reaction can be easily identified and the convergence is developed.

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The lateral spreading of a sandy ground destroyed pile foundations and the underground piles. The mechanism of lateral spreading is not clear because the mechanical properties of liquefied sand are not clear. Therefore, the authors developed a new torsional loading apparatus that was able to load until about 100% shear strain. By using this tester, the mechanical properties of liquefied sand were analyzed. On the basis of loading results, the mechanism of a lateral spreading was studied. The stress-strain curve of liquefied sand was formulated and a lateral spreading was numerically simulated. The results of the numerical simulation were compared with the results of the centrifuge model test. Both results were very similar t o each other.

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The vibration performance of penetration piles into the ground has not been discussed in detail so far. In this paper, monitoring of vibration performance of penetration piles—reaction force of pile tip and acceleration of pile top—is carried out at various grounds conditions. Analyzing the monitoring data, it is elucidated that the vibrating motion of reaction force of pile tip can be classified into such five categories as sinusoidal force domain, half-sinusoidal force domain, impact jumping domain, unstable jumping domain and transition period domain.

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The laboratory tests have been performed in order to investigate the effects of temperature up to 300°C and pressure up to 30MPa on the mechanical properties of three types of rocks, Inada granite, Sanjoume andesite and Oya tuff. The experimental results indicated that the significant differences in temperature dependence of mechanical properties exist between the three rocks, because of the difference of the factors which determine the mechanical properties of the rocks. The effect of temperature on the mechanical properties for the rocks is lower than that of pressure and water content. Temperature dependence of the mechanical properties is reduced by increase in pressure in the range of pressure and temperature investigated in this paper.

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A series of cyclic torsional shear tests has been carried out to investigate the effect of drainage with preshearing on behavior of dense sand. The results of experiment indicate: (1) the magnitude of excess pore pressure and shear strain after drainage history is influenced by both the principal stress direction and the magunitude of cyclic stress ratio at cyclic loading, (2) the variations of excess pore pressure and shear strain with number load cycles after drainage history depends on principal stress direction, (3) recompression volumetric strain due to dissipation of cyclic-induced excess pore pressure can be related to the maximum shear strain observed during cyclic shear, irrespective of the angle of principal stress direction, cyclic stress ratio and drainage history.

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The extended Bayesian method based on ABIC, is applied to inverse analysis of a regional groundwater flow model using unsteady flow observation data of Muika-mati area in Nigata-ken, JAPAN. In this study, observation wells is concentrated to the central part of the regional groundwater model, and it is important to cope with this ill-posedness. Thus, the prior information whose relative weight to the observation data is appropriately adjusted for by ABIC is introduced. The most important outcome of this study is verification of the prediction capability of the selected model by actually calculating the observed head changes of the aquifer system by the alternative models. The results are compared to the actual values, and verified.

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A resolution of usual measurement of sound velocity was an order of 1 per cent. However, when the monitoring of rocks for the long term period was considered, higher resolution was needed. We developed, therefore, a precise measurement system of sound velocity in rockmass by using piezoelectric transducer.
We measured a sound velocity by this system at Kamaishi mine, and concluded that the system was applicable to monitor rockmass for long term, e. g. hundred years of underground structure, because it have 0.003 resolution.

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It is presented how to derive the grain size distribution from the particle weight distribution based on the assumption of logarithm normal distribution and experiments. From extending these converts, mean particle size and mean radios of pores around solid particles are derived and related to coefficient of permeability. Finally, the mean pore size index concepts are summarized as a series of equations for predicting coefficient of permeability and drawing the permeability profile including clay soil.

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The purpose of this study is to evaluate the mechanical properties of cement-treated soil. Shear strength and failure criterion of cement-treated soil were investigated by performing normally and over consolidated triaxial compression tests. It was learned that shear behavior of normally consolidated cement-treated soil depends on the relative magnitude of σ'c/pc (σ'c is effective confining pressure and pc is consolidation yield stress), shear behavior of over consolidated cement-treated soil is influenced by OCR (over-consolidation ratio) and σ'c/pc. And failure criterion of cement-treated soil should be described with peak and residual strength line which have no reference to OCR.

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Measurement of impact acceleration of ram, earth pressure and ram penetration of ground was carried out under a variety of ram mass, ram base area and drop height in a series of the laboratory compaction tests. The waveforms of ram acceleration for the cases where the ram mass per unit ram base area is the same show a similar form, although the waveform changes remarkably with changes of the ram mass and ram base area. The waveform has two peaks; the first one is considered to be dependent on the elastic behavior of the soil and second one on the plastic behavior. The former can be interpreted in respect of the ram momentum and later in respect of the kinetic energy of the ram.

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A series of field and laboratory tests of ram blow to confirm that the impact force and compaction of sandy ground are dependent on the ram momentum rather than the kinetic energy were carried out under a variety of ram masses from 1.25kg through 25t and of ram base area and drop height. The waveform of ram impact acceleration was predominantly dependent on the ram mass per unit area of the ram base, and the effect of drop height on the waveform was less as expected from previous laboratory tests. The maximum impact acceleration, maximum impact stress and the ram penetration of the ground were well interpreted by the proposed mathematical models.

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The surface layers of alluvial plains in Kagoshima are almost covered with the alluvial secondary Shirasu which is eroded by the rainfall, transported from the Shirasu plateaus and deposited on the alluvial plain. Shirasu is classified into sandy soil, but its mechanical properties is different from usual sandy soil. In this paper the geotechnical properties of alluvial secondary Shirasu ground are investigated from various in-situ test results, which are summarized that (1) twice of N-value might be used to estimate the internal friction angle, (2) twice of N-value might be used to estimate the velocity of S-wave and (3) more resistance due to skin friction for piles might be expected for the alluvial secondary Shirasu ground than usual sandy ground.

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A series of centrifuge model tests using three model flexible pipes with different flexibilities yielded accurate earth pressures and quantified effects of the following factors on the behavior of buried flexible pipes: pipe flexibility, type of pipe installation, and ground material. The tests indicated that: (1) high earth pressure concentration occurs on the tops and bottoms of rigid pipes, and with an increase in the pipe flexibility, this pressure concentration relaxes to produce greater pipe deflection, (2) such tendency is drastically strengthened by the sheet-pile extraction when pipes are buried using an open excavation method with sheet-piling, and (3) the behavior of buried flexible pipes depends on both deformation and strength properties of the ground materials.

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In order to investigate the particle breakage properties of volcanic coarse-grained soils appeared at consolidation and shearing, a series of one-dimensional and isotropic consolidation tests, triaxial compression test and plane strain test were performed on four kinds of Hokkaido volcanic soils. Experimental results showed that there is a unique relationship between increment of finer content ΔFc produced by particle breakage and effective mean principal stress. It was also shown that the particle breakage characteristics of volcanic soils depend strongly on the effective stress path during consolidation and shearing. ΔFc induced in arbitrary stress paths can be estimated only by effective mean principal stress and effective stress ratio.

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In order to study the effect of fines on the liquefaction strength of reclaimed ground, laboratory tests, including triaxial and torsional dynamic tests and triaxial undrained static tests, were carried out using Toyoura sand mixed with non-plastic silt at various percentages, as well as decomposed granite soil sampled from Port-island in Kobe-city which had been liquefied during the 1995 Hyogoken-Nambu earthquake. Even though samples were all compacted up to 65% relative density, mixing of fines caused the general loss of liquefaction strength in spite of the increase of dry density. The reason for this was discussed in terms of individual void ratios by coarse and fine grains, and was examined by observing carefully the microstructure by means of thin sections and a microscope.

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Three series of centrifuge tests for simulating a process of shield construction in dry sand were performed by using a miniature shield machine developed by the authors, with special reference to tail void thickness and cover/diameter ratio. Each series models different ranges of construction process, ‘buried pipe test’ refers to measure the lining stress under a centrifugal acceleration, ‘tail void formation test’ simulates the process of tail void formation only, ‘shield test’ deals with the complete process of shield construction. Experimental formula for estimating the surface settlement above the shield was deduced by a function of tail void thickness and cover/diameter ratio. The lining stress at crown was successfully predicted by Terzaghi's loosing earth pressure, provided the measured Ko value was used.

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An effective stress model which can evaluate the undrained cyclic shear behaviour of sands and clays is proposed in this paper. The model is constituted of effective stress ratio and strain model and an effective stress path model which is developed by using the cyclic strength curves of soils. Cyclic mobility behaviour can be reasonablly simulated in the model. A response analysis was performed on the site where liquefaction was happend and seismic motion was recorded by borehole array during Great Hanshin Earthquake by applying the proposed model. Accuracy of the model was verified by comparing the analytical result with observed one.

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