This report considers the practicality of a soil assessment technique based on sounds generated during rotary sounding by applying the technology used in a shield tunneling. Laboratory experiment, model ground experiment and numerical analysis have been executed. The results of them have revealed that it is possible to quantitatively assess the difference in the sounds recorded for different soil types to estimate their grain size distribution.

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In test for maximum and minimum density of sands (JGS T 161-1990), the sand of which the maximum particle size exceeding 2mm is outside coverage. However, there are many occasions to handle such sand exceeding 2mm in practice. Therefore, we propose the test method for maximum and minimum density of the sand of 2mm or more in the maximum particle size by the following two methods. (1) Using the larger mold. (2) Application of the limitation method of the maximum particle size where the particle size distribution of sand is considered. And we prove that the proposed method serves enough to practical use.

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A new type of model “Pseudo-Rectangle Element Model” using two-dimensional circular element is proposed for the Distinct Element Method so that it can analyze not only motion of granular materials but also fracture of continua. The contact surface between two elements are divided into some sections, and the piecewise discrete spring and dashpot are disposed on each section. The numerical results are compared with the results of another methods and with experiments for a rectangular block on a slope and for a bending test of concrete mortal. Those comparisons represent the usefulness of the present model.

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The authors have newly developed a numerical inversion method using a fracture network model. In this method, fracture network system identified in geological survey is modeled as a channel network of flow paths.
Through the numerical experiments with fracture network model on a scale of field application, the authors examined applicability of the method to actual investigations. As a result, hydraulic conductivity distribution was reconstructed successfully.

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A laboratory test method is proposed in order to determine the lateral earth pressure in soils and its subsequent reduction with the lateral soil extension that probably occurs during an excavation. It is found that the in-situ earth pressure in overconsolidated pleistocene sandy soils has a significantly small K₀-value, and its reduction rate with the lateral extension tends to increase as OCR-value increases, but the developed active earth pressure depends strongly on the angle of internal friction, irrespective of OCR-value. From the experimental findings, a simplified method is suggested for the evaluation of the in-situ lateral earth pressure in pleistocene sandy soil deposits and its change during an excavation.

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In this study, the Eulerian-Lagrangian method was extended to a three dimensional mass transport problem for a density dependent saturated-unsaturated flow. Validity of this method was proved in comparison with experiments and anther 3-dimensional program (3DFEMFAT). A new algorithm was also proposed here. It decreased a computation time sharply compared with a usual algorithm.

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A simplified method is proposed to evaluate the ground deformation due to liquefaction-induced flow. Under the assumption that liquefaction-induced flow occurs slowly after the main shaking, stress-strain relationship after liquefaction is obtained through the laboratory test in which sand sample is subjected to monotonic load after subjected to cyclic load causing liquefaction or more. Stress-strain curve is shown to be quite different from the conventional one under small strains. The curve is separated into small rigidity region and rigidity recovering region, and is modeled to be a bi-linear model. Rigidity in small rigidity region is evaluated both by laboratory test and back analysis of earthquake damage, and is expressed as the ratio to the initial modulus. The modeling of the ground other than liquefied layer, such as nonliquefied ground above the liquefied layer, is also proposed based on the back analysis of the earthquake damage. Three case studies are conducted: Showa-ohashi sate, Uozaki-hama site and Aoba-cho site that were damaged during the 1964 Niigata, 1995 Hyogoken-nambu, and 1983 Nihonkai-chubu earthquakes. The proposed method predicts liquefaction-induced ground deformation well.

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With the expansion of the elevated road network in urban areas, there has been a strong demand for reduction of traffic-induced vibrations. However, an effective vibration reduction technique is not yet established. This study investigates the effectiveness of EPS (expanded polystyrol) underground wall in reducing traffic-induced vibrations. Firstly, a series of model vibration test is performed to obtain the dynamic characteristics of EPS. Secondly, we constructed an EPS underground wall, and conducted field vibration tests using a test car. Finally FEM simulation analyses were carried out and the comparison between the test results and analytical ones were made.

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Recently, several static rock fracturing (non-blasting) methods have been developed because of the increase of rock excavations near residential area. However, these methods lack methodology for fracturing design; how to design line of least resistance and spacing of fracturing holes according to the capacity of the fracturing system.
In this paper, stress intensity factor (K_I) of a fracture produced by our Aqua-sputter was calculated using a two-dimensional boudary element method.
The results showed that the most appropriate layout of boreholes can be determined from the minimum stress intensity factor of the fracture if fracture toughness of rock mass is known.

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To make the mechanism of shallow tunnel face failure in sandy ground clear and establish the evaluation method of the face stability, gravitational and centrifugal model tests were performed. Also the face stability was analyzed by the 3-dimensional limit equilibrium method, and the result was compared with the experimental one. The relation between the face stability and the overburden was shown through the result of tests and analysis, and the way of elavulating the face stability using the strength parameters of ground, unit weight, and tunnel diameter was proposed.

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There had been very few records on damages of steel pile type piers in previous earthquakes. However, several piers located in front of gravity caissons were damaged during the 1995 Hyogoken-Nambu Earthquake. Damage of piles at the site suggested that the lateral flow of the ground might accelerate the failure of the pier. In this study, centrifuge tests were firstly carried out to simulate dynamic behavior and failure of a steel pile type pier damaged in 1995 Hyogoken-Nambu Earthquake. And also some tests with different ground conditions were conducted to discuss the effects of liquefaction of the sand layer under the rubble mound on the lateral flow of the ground and the effect of the approaching plate connecting gravity caisson to ther pier on the dynamic interaction between the two structures.

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In this paper, a seismic prospecting and a seismic response analysis are performed for a damaged fill slope and a non-damaged fill slope on inclined basement rock due to the Hyogo-ken Nambu earthquake, and the instability mechanism of the slope during the earthquake is discussed. The main cause of instability of the fill slope is the amplification of acceleration and the concentration of shear strain in the part between the basement rock and overburden. The former causes small failures such as damage to stone masonry, and the latter causes large failures on the inclined basement rock. Also, the concentration of shear strain is closely related to the thickness of the overburden.

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This paper deals with a method for estimation of a spatial liquefaction potential and evaluation of liquefied ground flow. This method is based on a geostatistical procedure which is called as Kriging technique using variogram. It was applied to the liquefied sites after the 1995 Hyogoken-Nambu earthquake. Horizontal ground displacements at the plane reclaimed ground that were not due to the influence of the inclination of ground surface and movement of quay wall were especially investigated here. As a result of estimation of spatial liquefaction potential, it was clarified that the magnitude and direction of liquefied ground flow were influenced by the condition of spatial spread of liquefied area such as thickness of liquefied layer and inclination of boundary between high liquefiable potential layer and others.

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The objective of this paper is to evaluate the mutual influence of constructing adjacent boxy tunnels in the sandy soil using centrifuge model test. In the case three boxy tunnels are constructed very closely and the center tunnel of these tunnels is first constructed, it is appeared that the average earth pressure acting on the top of the boxy segment is larger than overburden pressure at the same depth if this depth is twice of the width of the boxy segment. But if the depth is 4.8 times larger than the length of the boxy segment, the average pressure is less than overburden pressure.

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It is well known that geomaterials exhibit quasi-elastic stress-strain behaviour at small strains. The stiffness in this small strain region is herewith termed as pseudo-elastic modulus. A laboratory investigation was performed into the pseudo-elastic modulus of reconstituted clays by considering some influencing factors such as consolidation history, drained creep, loading condition (i. e. strain rate, monotonic and cyclic loadings). On the basis of results of a series of undrained triaxial test performed, the variation of the pseudo-elastic modulus with each influencing factor was successfully expressed in a quantitative fashion by examining the e-logp' relationship of the clays when subjected to both consolidation and swelling.

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The method of sampling and analysis for underground gas is not yet establiished, in spite of that the gases encountered at underground work are not in single-component but multi-components in many cases. In this study, we propose 1) BAT System developed by B. A. Torstenssen, Sweden, is effeffecttive for underground gas sampling and 2) quick quantitative evaluation of all components in respective phases can be achieved through monitoring on the basis of phase equilibrium theory of non-reactive underground gas sampled. Furthermore, we found each component in respective phase can be represented in temperature-pressure relation assuming mole fraction of gas component is same. Consequently, concentration of underground gas became able to be predicted precisely regardless if the ground is saturated or not.

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In order to study the liquefaction characteristics of decomposed granite soils, a series of cyclic triaxial tests was carried out. Decomposed granite soils in Kansai area have a variety of grain size distribution as well as mineral composition and therefore, their engineering properties are also diverse. The liquefaction characteristics of the decomposed granite soils are influenced by the characteristics of soil particles themselves (amount of fine particles, the average grain diameter, coefficient of uniformity), the degree of weathering (ignition loss) and the consistency characteristic (flow limit).
The test results indicate that the liquefaction characteristics of decomposed granite soils differ remarkably each other depending upon geographical conditions, and those characteristics are closely related to the consistency of the soils. The liquefaction strength can easily be estimated by two factors i. e. the consistency (Wfl) and the void ratio after consolidation.

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This paper describes a new technique of local strain measurement using heat shrinkable tubing for wet or highly imhomogeneous rocks. This technique, assuming that a specimen and the tubing are uniformly deformed, is to measure the axial and circumferential strains on tubing under deformation using ordinary strain gauges. The measured strains are converted into the strains on specimen. The validation tests under uniaxial and triaxial compression are carried out with dry and wet Tage tuff. The magnitude of confinement due to wrapping the specimen by tubing is also examined. This technique can be utilized as an easy method to simultaneously determine the elastic modulus and Poisson's ratio of wet or highly imhomogeneous rocks.

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RI-cone penetrometers have been applied to sandy deposits to detect the natural water content and wet density profiles. Soil freezing sampling technique has been used to obtain the undisturbed sand samples and the laboratory experimental results on these samples are compared with RI-cone measurement. RI-cone measurement agrees well with the laboratory experimental data. The validity of RI-cone measurement is also confirmed with the calculated performance for the process of RI-cone penetration in terms of Eulerean finite element analysis. Relative density, D_r can be derived from RI-cone measurement. The accuracy of derived D_r has been confirmed with the laboratory experimental results on undisturbed samples.

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Excavation of shield tunnel was deemed as a combination problem of the ground condition and tunnel linings. A two-dimensional linear elastic FEM was used to incorporate lining-members in structuring an analytical model. The analysis separated the redistribution process of the loading due to excavation into two phases, viz. prior to the loading and after the loading to the linings. The rate of stress release prior to the loading is defined in the analysis as the stress release ratio.
It was shown that soil properties and construction factors determine the stress release ratio. The analysis was applied to four tunnels that run closely together. Verification was carried out by comparing the numerical analysis with monitored results on site with regard to such factors as the acting earth pressure and section stresses of a preceding tunnel itself and the variation of those factors in the course of the excavation of the succeeding tunnels.

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The authors performed a series of pullout tests to elucidate the reinforcing mechanism of steel grid reinforced earth and to evaluate the bearing resistance mobilized on transverse members. The bearing resistance was major part of the total pullout resistance in the steel grid reinforced earth, which was equally mobilized on each transverse member in case of wider interval between transverse members than 200mm and increased in proportion to the number of transverse members. It is because longitudinal members of steel gird reinforcement hardly extended during pullout tests and all transverse members equally displaced. Considering the bearing resistance characteristics of steel grid reinforced earth, the authors proposed an equation to estimate the bearing resistance which was based on the bearing capacity theory. The applicability of the proposed equation was confirmed through the comparison between analytical and experimental test results for both frictional and cohesive-firictional backfill soils.

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The Hyogoken-Nambu Earthquake gave serious damage to foundations located on the Hanshin Expressway No. 5 Bay Route that connects many recently reclaimed islands, together with causing greater residual ground deformation and residual lateral displacement of piers near waterfront. In this paper, were described the details of damage condition of piles and its relationship with the seismic response displacement of the ground that was calculated using one dimensional earthquake response analysis. As the results, it was concluded that cracks were concentrated at pile top and around pile surface at the boundary of soil layers, and that cracks were caused mainly due to the seismic response displacement of ground, especially at around revetments, the lateral flow displacement of ground was an aditional cause.

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In situ soil investigations were carried out at Tsuruga and Tomakomai sites using CPT, DMT, SFT and seismic cone penetration tests. Tsuruga site consists of reclaimed land filled with finely crushed rock aggregates, while Tomakomai site comprises the secondary sedimentary deposit of volcanic ash. Both the sites are characterized by granular materials having mean particle size considerably larger than 2mm. Various soil parameters obtained from these in situ tests have been correlated with each other, and the correlations compared with the already established ones for the sandy grounds. It has been found that DMT cannot be applied directly to grounds having large size soil particles.

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In order to grasp the mechanical behavior of shallow tunnel excavation in the intersection, three dimensional trap door tests have been developed and performed. Dry sand (Hamaoka sand) has been used for ground material. With changing overburden pressures, the width of trap door and the intersection angle between tunnels, the variation of vertical earth pressure acting on trap doors, the distribution of earth pressure and the settlement of ground surface have been measured. Based on the experimental results, it has been confirmed that the variation of earth pressure with moving the branch trap door has been strongly affected by the initial overburden earth pressure and the intersection angle. Then, three dimensional earth pressure theory has been suggested using Terzaghi's earth pressure theory and its application has been discussed in the experimental results.

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The stability analysis of the tunnel heading is studied by means of the rigid-plastic finite element method which is exclusively applicable to the behavior of the critical state of the surrounding ground of the tunnel. It is confirmed that the apparent cohesion of the soft sandy ground, even if it is of a small value, plays an important role to sustain the stability of the tunnel face as was pointed out by Mashimo. The effects of the existence of the un-supported region and the pre-lining on the stability are also considered in relation to the required minimum value of the apparent cohesion.

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Soils from sand boils formed during earthquakes were collected and examined to investigate the grain size distribution of the liquefied layers in the ground. However, such effectiveness of sand boils as an index has been questioned, since several observation results of sand dikes excavated in ruins revealed that the grain size distribution of soil in sand dikes differs from that in liquefied layers. In this study, the authors investigated the physical properties of soil in sand dikes, the mechanism of sand dike formation, and the relationship between sand dikes, sand boils and liquefied layers at three sites having liquefied during two earthquakes. As a result, soil particles in sand dikes were found sorted, being coarser in the lower part, and did not coincide with the grain size distribution of the soil particles in the liquefied layers or in sand boils. However, the grain size distribution of soil in sand boils was similar to that in the liquefied layers.

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The characteristics of interaction between cohesive soil and geogrid is investigated on the basis of the pull-out test results of geogrid in soil. The pull-out resistance acting between cohesive soil and geogrid can be divided into two parts; the one is dependent on a displacement of geogrid while the other is independent of it. The analytical method introducing its characterististics of interaction between cohesive soil and geogrid into a finite element method is proposed and its validity is verified. From the comparison between the analytical values and the measured or experimental values, it is proved that the behavior of reinforced cohesive soil ground by geogrid can be analysed well by means of the proposed method.

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One of the indices for rock mass classification deals with “judgment method by the hammer tapping”. It has been based on qualitative evaluation rather than the quantitative one. In the course of our study, it was observed that the quantitative evaluation of the properties of rock is established by analyzing the vibration of the tapping sound wave obtained from measurements by a microphone. From the analysis results of the fundamental experiments (using the artificial rock), we propose an approach, “response sound pressure pulse inclination”, as one of the quantitative evaluation indices for rock classification.

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The air-cement treated soil (ACS) is one of the typical lightweight geomaterials, which has a few merits as making good use of waste soil or countermeasure for soft ground. The evaluation method of the ACS has not been generalized because of the variety of the factor to fix its property. Unconfined compression strength was selected out as an index to evaluate the ACS in this study.
As a result, it was shown the unconfined compression strength of the ACS decreased exponentially against the void ratio. Then, using a relationship of the two indices we found the following fact. Namely, cement ratio in the high level, curing term exceeded 56 days and mixing method gave less effect. Confining pressure when the ACS was fresh, however, gave a great influence to the unconfined compression strength.

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Pulse interaction with a partially contacting plane of weakness (interface) is investigated experimentally as well as numerically. The interface is subjected to static pre-stresses. Using dynamic photoelasticity in conjunction with high speed cinematography, the evolution of the dynamic interaction is recorded by means of isochromatic fringe patterns (contours of maximum shear stress). It is shown that interface slip can be triggered by a pulse that propagates along the interface at the relevant Rayleigh wave speed. Numerically, a finite difference wave propagation simulator SWIFD is used to discuss dynamic rupture in laterally heterogeneous structures by considering the effect of acoustic impedance mismatch. The results indicate that upon interface rupture, Mach waves, which carry a relatively large amount of concentrated energy, can be generated and propagated off the interface contact region (asperity). Such Mach waves can cause concentrated wave-induced damage in a particular region. It is possible that the “damage belt” found in Kobe. Japan, on the occasion of the 1995 Hyogo-ken Nanbu earthquake, was generated by Mach waves.

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The stability of Japanese castle masonry walls is determined by their 3 dimensional levels i. e. height, gradient, thickness and average density, and the stone piling-up techniques of respective time of construction of m. w.. The stability of the 3 dimensional levels of m. w. is analyzed by applying the lean-type wall design method. The stone pile-up techniques depend on the skill of cutting out stones, pile-up methods and filling condition of stones.
The stability reducing coeff. fn for these factors are introduced. The m. w. coeff. F which is obtained by multiplying these reducing coeff. fn, is expected to indicate the stability of m. w..

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The excavation of shallow tunnels in unconsolidated grounds causes non-linear displacements in many cases, which leads to a serious problem. In this paper the authors defined and analyzed these displacements by reducing the shear-stiffness related to the shear-strain in geo-materials. They applied this procedure to simulate actual soil behaviors, and succeeded to demonstrate the practical applicability. Further the authors analyzed the non-elastic volumetric changes together with this procedure and concluded that the vertical displacements between ground surface and tunnel crown are more precise with the measurements than the case using only anisotropic damage parameters.

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In general, tunnels in very poor rock are driven by the short bench cut method. However, to limit the deformation of tunnel side walls and roof, the micro bench tunneling method, utilizing face bolts as auxiliary measures, will be required. From this view of point, three dimensional finite difference analysis was carried out to simulate the rock behaviors around the tunnel face. Analytical results indicate that fully grouted face bolts are available to reduce the deformation of the tunnel face, and the extent of the plastic zone around tunnel face.

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