In order to investigate the pre-stress of rock mass by applying the Kaiser effect of AE (Acoustic Emission), three kinds of experiments were performed on the granite specimens subjected to creeping under a constant load until their creep strain ceased. Such condition of the specimen was designated as the “strain saturated condition”.
Obtained results are as follows:
(1) If the specimens were in strain saturated condition, the applied loads were able to be estimated almost correctly by the Kaiser effect.
(2) When the specimens in strain saturated condition were left under various loads less than the initially applied creep loads for some periods and the residual strains decreased, the stresses estimated by the Kaiser effect became less than the applied load according as the decrease of residual strains.

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When the large cutting slopes are constructed closed to arround nuclear power plant, it is important to evaluate the stability of the slopes during the strong earthquake. In the evaluation it may be useful to clarify relationships between the static seismic coefficient and dynamic seismic force corresponded to the basic seismic motion which is specified for disigning the nuclear power facilities. To investigate this relation some numerical analyses are conducted in this paper. As the results, it is found that dynamic forces considering the amplified responses of the slopes subjected to the basic seismic motion with a peak acceleration of 500gal at the toe of the slopes, are approximately equal to static seismic force which generates in the slopes when the seismic coefficient of K=0.3 is applied.

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A micromechanically based constitutive equation is formulated based on a slip model in which multi slips are assumed to take place instantaneously. The proposed multi slip model can account for many aspects of deformation characteristics of granular materials. The numerical calculation results accord well with experimental results in a qualitative manner. As a simplified version of the proposed multi slip model, ‘Double slip model’ is modified so as to account for the anisotropic hardening nature of granular materials. The applicability of the model is discussed to some extent from a phenomenological point of view. In order to asses the limitation of the model, the physical ground of the slip model, as a micromechanism for granular materials, is critically discussed.

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A new photoelastic experimental method for displacement measurement on rough surfaces of opaque materials was developed. In the method, a surface of a test specimen, such as that made of weak rock, mortar or soil, is coated with photoelastic transparent polymer, and the surface of the polymer coating is fixed by a rigid transparent plate. Accordingly, displacement on the surface of the test specimen is transformed into shear strain in the photoelastic coating. The shear strain induced in the coating can be easily detected by analyzing dispersive photoelastic fringes which appear when a polarized laser beam parallel to the surface of the specimen passes through the coating. This method can be expected as one of the simplest and useful methods for detecting minute deformations of opaque specimens.

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A simple formulation is proposed by using shear works to express the development of pore water pressure under cyclic stresses. The proposed formulation is derived from data of the cyclic triaxial tests with various confining stresses and relative densities on a saturated sand. The pore water pressure model can be easily coupled with a nonlinear model to perform the liquefaction analysis for saturated sand deposits. The analysis, called W_s method, is a simplified effective stress analysis, calculating pore water pressure every half cycle. The method is compared with a nonlinear effective analysis, which is called the equi-W_st-line method and evaluates the pore water pressure by every time step.

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Surface subsidence due to a shallow sandy ground tunnel construction may affect the stability and safety of neighboring structures. To establish a design method for shallow sandy ground tunnels, it is very important to specify an analytical model which can synthetically explain not only the surface subsidence but displacement behavior in the surrounding ground as well. For the purpose, a series of finite elements analyses, i. e., elastic elements analysis, elasto-plastic elements analysis, no-tension analysis, and joint elements analysis, were carried out and their analytical results were discussed in relation to the following four points, those are (1) deflections of tunnel wall, (2) extent of plastic zones developed in surrounding ground, (3) the shape of surface subsidence, and (4) the ratio of the displacement at the tunnel crown to the amount of surface subsidence. The use of joint elements was found to be the most effective in the analysis of a shallow sandy ground tunnel construction.

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The authors studied for ten years with the research on granular soil which have needed strength and stability due to add fixing agent into the soil. The main purposes of this research are (1) prevent the growth of soil dust, (2) construct the pervious ground, (3) effective utilization for sludge from the filter plant.
The results from basic research were clearly found that there are suitable water content to granulate soils and those granulation of soils are able to be utilized as materials of construction.

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This paper aims to clarify the size effect of track performance of running gear on disturbed silty loam. The maximum tractive resistance F_max and the sinkage z_m to be predicted were analyzed by use of dimensional analysis and multiple regression method. Four kinds of geometrically similar rigid track model were used, and 171 cases of traction tests were executed on the silty loam of 30, 35 and 40% water content in a range of average contact pressure 0.98 to 9.80kPa. Considering the distorted design condition of soil properties when the model tests were executed on the same soil condition as that of prototype, it is clarified that the ratios of prototype (p) to model (m) are described as exponential functions of the geometrically similar ratio of track width B and grouser height H as, (F_max)_p/(F_max)_m=(B/B_m)^1.667 and (z_m)_p/(z_m)_m=(H/H_m)^0.954.

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In order to clarify the strength property of sands stabilized by silicate grout, We investigate the effect of negative pore water pressure U caused by dilatancy on the strength of stabilized sand and moreover the time-dependent strength behaviour. Through unjacketed tests, triaxial test, uniaxial creep test and so on, the main results are summarised as follows; 1) Effect of U on the strength of stabilized sand would be considerably large. The unjacketed test would be recommended to determine the strength of stabilized sands, especially where the injection region is below the ground water level. 2) The unconfined strength of stabilized sand in long-term load q_CR is less than 50% of q_u(ε₁=0.5%/min), q_CR is uniquely related to the strength of silicate gel, irrespective of density and grain size of stabilized sand.

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To elucidate the mechanical behaviour of sands strengthened by cementing materials, we investigate the relation between cohesion (i. e. cohesive bonds made by silicate gel) and dilatancy of stabilized sand in shearing process. In experiments, triaxial drained tests, triaxial undrained tests, and constant mean principal effective stress tests were performed. The conclusions are summarised as follows;
1) Although the dilatancy initiation of stabilized sands in shearing process is delayed by cohesion as compared with unstabilized sands, the dilatancy is much larger than that of unstabilized sands when the axial deformation increases to a certain degree.
2) Cohesion would be uniquely related to ε_vd (volumetric strain caused by shear stress increment only) rather than the shear strain, irrespective of the confined stress and drain or undrained condition.

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The Main object of this study is to clarify the cation adsorption-desorption properties in the salt water intrusion. Chemical hysteresis between adsorption and desorption process is found by the laboratory test. It is revealed that adsorption process is generated by the ion exchange and the effect of electrolytic concentration and desorption process is only affected by electrolytic concentration decreasing. The numerical analysis of dispersion problems involving the cation adsorption-desorption is carried out for solving example problem of the ground water contamination. It is clearly seen that the cation adsorption-desorption largely affects in the range of low concentration from salt water intrusion.

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The Shimajiri mudstone (silty clays) is widely distributed in the southern and central parts of Okinawa Island. The Shimajiri Formation, mostly of the Shimajiri mudstone, is marine deposit of Miocene-Pliocene epoch. The present paper deals with the results of experimental studies on the stabilized soils for the effects on CBR mainly. Discussions are made on the test results comparing with those materials; (1) the natural clays passing through square opening of 38.1mm, (2) the clay-cement mixtures and (3) the clay-hydrated lime mixtures. It is clarified that the stabilization effectiveness is closely related to the mixing water content, the additive content, and the curing time.

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A model is presented which describes fully coupled hydro-thermo-mechanical behavior of porous geologic medium. The mathematical formulation for the model utilizes the Biot theory for the consolidation and the energy balance equation. The medium is in the condition of saturated-unsaturated flow, then the free surfaces can be considered in the model. A two-dimensional finite element code was developed under the assumptions that the medium is poro-elastic, in plane strain condition and water was not subjected to phase changes. Example problems are analysed. The one is a study of some of the effects of completely coupled hydro-thermo-mechanical behavior on the response of a saturated-unsaturated porous rock containing a buried heat source. Applicability of this code will be given in detail in the paper.

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To observe how dilatancy of rock localizes before faulting, we attempted to map the P wave velocity field (seismic profile) of some sliced plane of the specimen by analyzing a number of the first arrival times. This technique, termed seismic CT, is useful to study the process of dilatancy localization, because P wave velocity is influenced by the extent of dilatancy. Here, we present the results of reconstruction made on the specimen of Ohshima granite within the plane parallel to the loading axis. The specimen was once compressed beyond the maximum load carrying capability under uniaxial conditions. The map clearly shows that the shape of the localized dilatancy determines the mode of failure, which occurs by faulting inclined to the specimen axis on conjugate faults.

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Seismic CT (computer tomography) was applied to visualize water infiltration into the specimen of dry granite. The spatial distributions of both P wave velocity and the change in attenuation coefficient (seismic profiles) were determined. When the microcracks within rock are filled with permeating water, the effective bulk modulus of rock increases, hence P wave velocity increases. Attenuation is also influenced greatly both the degree of saturation and the flow type of water within the microcracks. As a result, we can observe the spreading water through the interconnecting microcracks by reconstructing the seismic profiles. The location of the wetting front is successively determined by the reconstruction of the change in attenuation coefficient. It is now possible to map nondestructively the interior of specimen with seismic CT.

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New concept of effective stress for unsaturated soil is proposed. It is assumed that the effective stress consists of two components. One is (σ-u_a), which acts as if (σ-u_w) of saturated soil and when soil is saturated, u_a=u_w is assumed. Another one is suction. It controls not only water content but also soil constants such as c' and m_v. To prove above concept and to look into the relationship between suction and soil constants, drained (suction controlled) triaxial compression tests, including anisotropic consolidation and repeated loading, were performed on compacted Kaoline. When suction is kept constant, it seems that volume change and water content of sample are given only by the present stress state. Unified stress-strain equations were obtained using a factor α, which is defined by the new effective stress.

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Granite contains many small defects which are preferentially oriented along three mutually perpendicular planes. These defects affect the physical properties, of the granite, e. g. P wave velocity, compressive strength, tensile strength.
In this study, we are reporting the relation between the physical anisotropy and the microstructure of granite. Oshima granite was chosen for this test. P wave velocity was measured in diametric directions at 15° intervals. The diametric compression test was performed under the same condition. Three thin sections were cut (one parallel to the rift plane, one parallel to the grain plane and one other parallel to the hardway plane) to check the preferred orientation of small defects.
There was a strong correlation between the strength anisotropy, the preferred orientations of open microcracks in quartz and P wave anisotropy and there was also a correlation between the tensile strength anisotropy and the healed microcracks in feldspar.

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In this paper, the consolidation behaviour of a hollow cylinder under seven kinds of deformation condition is examined assuming the anisotropic stress-strain relation of the clay skeleton. That is, a consolidation equation is induced, and then, giving its solution, the effects of anisotropy and deformation conditions on its consolidation behaviour are considered.
As a result, the authors clarified the following facts: the form of consolidation equation of transversally isotropic hollow cylinder becomes entirely the same as isotropic hollow cylinder; the rate of consolidation is depends on the ratio of outside and inside diameters of hollow cylinder, anisotropy and deformation conditions; etc.

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This paper discribes a reliability-based procedure for selecting a countermeasure against a failure of a slope. The type of failure considered in this paper is a sliding slope failure due to a ground water flow during dry-up operation of the graving dock. Firstly, a proposed countermeasure consists of a series of horizontal drainage pipes. Optimum design is selected among relevant alternatives with various horizontal drainage pipe spacings. A widely accepted criterion for optimum decision is the minimum expected cost, which directly incoporates qualitative evaluation of safety in terms of failure probability.

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Recently a multiple-purpose utilization of heated water which is produced by utilizing the exhausted heat from waste incineration equipment, solar energy and geothermal energy, is now being put into practice in Japan. One of the possible measures is temporary storage of heated water which is sent up from underground openings excavated in rock mass near the ground-surface. In this case, as the rock mass around openings would be affected by heated water, the stability of openings is an important problem. To investigate this problem, we need to know the strength and deformation characteristics of rocks affected by heated water. This paper describes change of rocks strength and deformation that were measured in heated water and at high temperature.

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This paper presents a method of constituting a rock mass classification, which is capable of representing an engineer's subjectivity on engineering judgement and thought process by using the fuzzy set theory. The method is composed of three parts; (1) description of judging classification parameters by fuzzy sets, (2) grading of importance of each parameter, (3) total evaluation of judgement of all parameters by fuzzy integral. The classification provides a distribution of “fuzzy expected values” covering all the rock mass classes (five classes, i. e. “very good”, “good”, “fair”, “poor” and “very poor”, are adopted in this paper). An example is shown to illustrate the constitution of rock mass classification by the proposed method.

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In this study experimental examinations were carried out in order to investigate the ground water condition to prevent the leakage of the compressed air from an unlined rock cavern as energy storage. As a result it was affirmed that the compressed air can be stored if the air pressure is lower than hydrostatic pressure around the unlined cavern, or, if the ground water flows with positive hydraulic gradient normal to the surface of the cavern. The finite element analysis, derived from the concept of the gasliquid two phase flow in the ground, applied to the investigation. The results reaffirmed the condition above mentioned and indicated that the numerical procedure proposed here is an effective tool to estimate the leakage of the air or gases from the storage caverns in the field.

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To clarify the possibility of underground LPG storage, the temperature-dependence of mechanical properties and frost heaving of rock are expressed as functions of temperature, and a method of heat conduction analysis and thermal stress analysis including material nonlinearity is developed using finite element method. As the result of computations for underground LPG storage, the failure around a rock cavern is produced as tensile failure and frost heaving exerts a great influence on the stability of LPG storage. In thermal stress analysis for underground rock cavern, it is necessary to represent the semi-infinite domain with an infinite element.

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In order to investigate influence of fabric of kaolin clay on secondary consolidation behavior, samples were prepared which have different fabrics, that is, samples with the addition of quanties of aluminum sulfate about 0-10%. The consolidation test were caried out for these samples under various conditions. Some of the obtained results are as follows: (1) The coefficient of secondary consolidation C_α increases with increasing the average size of peds P₅₀. This seems to suggest that the volume decrease of clay due to the compression of micro-pores in the secondary stage were predominated, owing to the number of micro-pores increases with increasing P₅₀. (2) The elapsed time t_s at which e-logt curves give straight lines is affected by Δp/p and P₅₀. Namely, t_s increases with increasing P₅₀, and these trends are predominated when Δp/p is decreased, but, t_s is not affected by Δp/p and P₅₀ when the preconsolidation pressure is increased.

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This paper presents newly developed two slice methods for slope stability analysis; Advanced Limit Equilibrium method and Janbu-h/3 method. They can be applied for both circular and non-circular slip surfaces. The Advanced Limit Equilibrium method gives a reasonable safety factor and a plausible distribution of interslice forces more easily than the Morgenstern & Price method. The Janbu-h/3 method gives a safety factor accurate enough for practical purposes, though it does not always give proper interslice forces.

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A series of physico-chemical and mechanical tests were performed on the soils sampled from peaty grounds in the suburbs of Iwamizawa city, Hokkaido and Ohmiya city, Saitama, and the geotechnical properties of peats and peaty grounds were investigated. The results of various physico-chemical tests were mainly summarized as a function of organic matter content involved. Also, using the samples of peats and humused chipes, the changes of pore volume and pore size distributions with the one-dimensional compression were investigated with the porosimeter apparatus. From the results of mechanical tests, it was found that the coefficients of secondary compression and permeability of soils were strongly influenced by the amount of organic matter and fibrous peats remarkebly showed anisotropic shear strength.

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The fill placement works on the dam foundation as overburden loading. This loading would influence the stress states in the foundation resulting in the change of strain and permeability in the underground. Therefore, the authors actually measured the deformation of dam foundation and the change of permeability due to the fill placement at two damsites. The results measured at both damsites indicate that the fill placement causes the compression of dam foundations accompanying the decrease of permeability. The authors feel that these results are very helpful for the determination of effective grouting design for the foundation of filldams. Furthermore, the authors theoretically try to explain the relationship between the compressive strain of the foundations and the decrease of permeability due to the fill placement by using the simple models.

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Japanese National Railways developed a new pipe jacking method for constructing an underpass across the railway embankment in 1976. But in earlier stage of its application, the excavation system could not penetrate the gravelly ground and in the worst case, even the cutter arm was broken. This compelled us to estimate the necessary cutter torque from the characteristics of the ground for a rational redesigning of the excavation system.

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The D301 pipe jacking method has been developed to be used in construction of conduits for communication cables.
This method has driving mechanism without muck discharge. Tunnel machine produces a cylindrical hole in ground by forward driving of closed head, into which following pipes are pushed. and a small diameter tunnel is set up.
This paper describes the applicable ground for this method with the view of estimation of driving force and soil behaviour in surrounding ground.

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