Today's increasing demand for land development can no longer leave vulnerable landslide areas untouched. Therefore, a rigorous method for this risk evaluation, if available, would be a valuable instrument for preventing landslide disasters in such development areas. Currently used conventional evaluation methods are empirical and qualitative in nature, largely depending on professional/pertinent expertise and judgement. In order to introduce some scientific rigor instead, this paper proposes a quantitative evaluation method, which (a) items from Hayashi's quantification theory with regard to relevant aspects (data items) connecting landslide risks, (b) classifies these items into a few categorical groups, (c) assesses the vulnerability of landslide in these items, (d) expresses the vulnerability in terms of the distribution of these data items in the multi-dimensional Euclidian space, and (e) evaluates the vulnerability as expressed by the distance measure between the eigenvalues which are respectively and uniquely determined for each category group in this space. This quantitative method, as well as the conventional method for comparison purposes, are applied to the vulnerability evaluation for Yuya district in Yamaguchi prefecture, well-known for frequent past occurrence and high risk of landslide. A significant consistency between the two evaluation results is found, including the applicability and practicality of the proposed quantitative method.

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A solution of the wave equation for the pile driving analysis by means of the finite difference method is presented in this paper. According to the method of solution presented here, the boundary conditions and the wave equation are differentiated and formed into simultaneous equations, and then the wave equation at the boundaries are solved. This method basically follows the same procedure as an analytical method and thus is able to obtain wave equations that stand good at any point of the pile system. Because of this, as long as the behaviour of pile system can be expressed by the one dimensional wave equation, it is possible to obtain the numerical solutions even though the pile system is complex.

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It is no doubt that the effect of water pressure and of water movement through the pores in geologic materials is of great practical importance. However, the realistic problem in the hydrogeologic modelling has not been analysed until the powerful numerical techniques such as FEM are invented. Solution methods f or three dimensional problems are still the big subject to be explored. In this paper a new quasi-three dimensional method (vertical slice method) to analyse groundwater problems is proposed. A medium is modeled by anassemblege of arbitrary numbers of vertial or inclined slices which are connected each other by one- or two-dimensional elements. Each slice is discretized by the usual two-dimensional finite element mesh. The whole system is solved by iteration process. The new method is evaluated by comparing with an analytical solution and is applied to the problem of flooding in tunnel excavation.

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In order to investigate the shear strength and dynamic deformation characteristics of gravels, we carried out the torsional simple shear tests (TSS), triaxial compression tests (TC), cyclic torsional simple shear tests (CTSS) and cyclic triaxial tests (CTX).
The results obtained can be summarized as follows.
1) Shear strength in TSS and shear modulus in CTSS are larger than those in TC and CTX due to the influence of intermediate principal stress.
2) Shear modulus and damping ratio are expressed as a function of shear strain, void ratio and confining pressure.
3) Elastic moduli in monotonic loading test and those in cyclic loading test agree with each other in Toyoura sand and gravels.

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Simultaneous monotonic and cyclic loading may be applied to a soil element near, for example, retaining structures during earthquakes. To study into the behavior of saturated sand in such a case as above, a series of undrained triaxial tests were performed by applying cyclic stresses to a specimen which is subjected to continuous monotonic loading at a constant axial strain rate simultaneously. It was found that the behavior of sand in these tests was different from those in other types of cyclic loading tests in which cyclic stresses are fully or partially reversed or not reversed between the triaxial compression and extension conditions.
Furthermore, a sort of interaction effect of cyclic and monotonic loading on the liquefaction was observed, of which the tendency depended on the density of specimen.

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The most concerned problem in pipe-jacking remained to be solved is to establish a stable and economical method of curving.
The author has devised a new curving method, which has solved practically, theoretically and economically the difficulties that may be involved in the technical processes of curving and proved the fact by the results of 15 works performed, after having shown how this method excels the conventional ones.

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The mechanisms of two-dimensional specific cutting resistance and steady excavating force for weak rock mass have been analysed by means of the failure criterion of rock materials. As the results, the specific cutting resistance could be estimated by Eqs. (11), (12) from the unconfined compressive strength, radial compressive strength, assuming that the shear failure develops on the whole linear slippage line on which the normal stress distributes to the power of 0.30 and the steady excavating force could be estimated by Eq. (28) from the unconfined and radial compressive strength, assuming that the shear failure develops on the logarithmic spiral and linear line on which the normal stress distributes to the power of 1.79. The steady cutting force could be expressed by the function of specific cutting resistance, depth of excavation and rake angle of the blade.

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The evaporation from soil surface and solute migration in an unsaturated zone above the groundwater are studied experimentally and theoretically. The experimental apparatus used in this study consists of a wind tube, soil column, groundwater feeding tank and a set of measurement equipments. The vertical profiles of solute concentration, temperature and water content along soil column, and the evaporation rate from soil surface are measured for different wind velocities.
The analytical solutions of governing equations at the steady state are developed for solute migration in coupling with heat transport and moisture movement. The comparison between analytical solutions and experimental results shows an excellent agreement. The results describe that the solute migration depends upon not only vertical movement of moisture but also a depth of capillary fringe.

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In many tunnels, icicles and side ices grow in cold climate. Against such a background we usually adapt an icicle prevention by adiabatic treatment for railway tunnel. We previously proposed optimum materials and optimum depth of heat insulator in consideration of statistical atomospheric conditions for the prevention. This paper deals with a thermal behavior of a near end of the heat insulator affected by the cold in non-treated area, and a marginal length which has to be set aside in length of the heat insulator. A two dimensional nonsteady state heat conduction tunnel model is proposed. After the analyzed values are found to well agree with the measured ones of an exisiting tunnel, we propose the marginal length for insulator width according to atomospheric conditions.

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Pile driving formulas based on the stress-wave theory are presented in this paper. The rigid body hammer and the elastic hammer with no cushion are used for hammer conditions and as the model of the pile base resistance, the rigid-plastic model and the elasto-plastic one are employed. Pile driving formulas presented in this paper and those of ordinary used ones are examined by using the results of the numerical simulation of the pile drivings based on the stress-wave theory. As the results of the theoretical analysis, the applicability of ordinary used pile driving formulas are better for cases which have long duration of the driving force. And it is also found that the applicability of the pile driving formula depends on the wave form of the driving force.

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Conventional oedometer tests with reduced duration of loading have been done on highly organic soil so as to know the influence of loading duration on consolidation indices of the soil. Loading duration was varied between 20min and 60min, and the test results were compared with those obtained from the standard oedometer test in which loading duration is 1440min. Followings were concluded from the tests.
(1) When a soil is in the normally consolidated region, rapid consolidation test gives almost same results with those obtained from the standard oedometer test.
(2) However, when a soil is in the over consolidated region, settlement predicted by rapid consolidation test is smaller than that predicted by the standard oedometer test.

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In order to investigate the slightly-long-period microtremors, the measurement of microtremors at the seaside region and the periodical observations of microtremors over two years at the basin of inland have been carried out. It is conjectured that the slightly-long-period tnicrotremors are due to natural disturbances such as the swell of the sea.
Microtremors are affected by sea waves even at the region 60km away from the seashore, but the microtremors on the deposit change in the same manner as ones on the hill. The ratio of mean amplitude on the deposit to one on the hill is almost constant for each site. The ratio corresponds to the amplification degree of earthquake movements by each deposit. This ratio is useful for geophysical exploration and seismic hazard analysis.

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In many tunnels, icicles and side-wall ices usually grow, and frost heaves at back of lining occur. This paper deals with some actual states of frost penetration depth in railway tunnels and its simulation analysis. First, daily fluctuations and maximum values of frost penetration depth are described about a few actual tunnels. Next, they are simulated by a tunnel ground model which is a one-dimensional nonsteady state heat convection/conduction difference equation considering the latent heat. The analytical results agree with the measured ones. Then using the tunnel ground model, behaviors of daily fluctuations, etc. of frost penetration depth are analysed against a yearly periodic change of atmospheric temperature in tunnel.

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In order to clarify the mechanism of microcracking due to thermal attack in inhomogeneous granite, AE (Acoustic Emission) was monitored during the small scale insitu heater test in an old quarry of Inada granite. An 2m long electric heater was inserted at the depth from 3.3m to 5.3m in a bored hole of the 100mm diameter, and the temperature of the heater was increased to 800°C. AE was monitored for 60 hours with 12 sensors buried in 4 holes bored 1m distant from the hole with the heater, and thus 636 AE hypocenters were located. AE hypocenters clustered in pegmatite intruded into granite and pre-existing joints. In addition, it was observed that the temperature in which AE started to occur was about 60°C in granite, which is the same temperature as other researchers previously reported on their laboratory experiments, while the temperature of AE generation was lower than 60°C in pegmatite.

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This paper aims to analyze the stability of elliptic tunnel generally, to make clear the relations between stability and various physical values of ground and tunnel support. The stability of elliptic tunnel is discussed from the point of distortional strain energy by using Airy's stress function on elliptic coordinates represented by complex variable. As conclusions, it was shown that the safety index of ground around elliptic tunnel in any construction stage is composed of 6 nondimensional factors and the factors included in the respective yield criterion. Based on the analysis of the factors, the stability and the support's effect were clarified quantitatively and the preliminary design method of elliptic tunnel was proposed. Furthermore, the results were applied to the measured data.

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The theoretical analyses of a triaxial elastic solid inclusion stressmeter are presented under the assumption of isotropic elastic medium with arbitrary elastic constants. The effects of grout layer thickness, interface sliding and overcoring diameter around a concentric pilot hole with the inclusion on estimations of ground initial or variable stresses are exactly expressed by closed-form solutions for the cases of three-dimensional stress systems. Numerical results for practical usage are shown by several refined graphical representations.

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The three dimensional geometry of the planes of separation sitting inside a discontinuous rock mass is of primary importance in analysing the stability of the rock slope consisting of ground surface and discontinuity in the rock mass. This paper proposes a method to handle such geometrical problem by dividing the rock slope into a number of small cubes. The location of the planes of discontinuity is also put into a computer by using a certain set of indices allocated to each of the cubes. The equilibrium of the forces acting on a block of rock which may possibly slide during/after construction work is then calculated in the computer following a proposed procedure. The proposed method of rock block identification and stability analysis is then applied to a case history of an actual slide of a rock mass caused by cutting of a slope. The result indicates that the influence of the ground water level on the stability of a rock mass is in accordance with the stability of the rock mass monitored during the construction work.

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For the purpose of improving the quality of life and saving enagy, heated water produced by using surplus heat from garbage-burning plant etc., will be utilized well in the near future for many purposes. To insure a stable supply, temporary storage in rock mass openings in mountain may become an important problem. In this study, stability and leakage of openings were estimated by analysis using the physical properties of rock which were obtained by experiment.

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This paper deals with an analytical interpretation of field performances of saturated soil deposit by using the back analysis procedure. We consider the elasto-plastic ground behavior as the consequences of nonlinear elastic responses where non-homogeneous regions and anisotropy will be expanded. Herein, we propose the equivalent tangential stiffness over the whole foundation as the parameters to be identified, and the changing status of the whole foundation is assessed by the interpretation of newly pursued parameters. We find an example of saturated soil deposit with various permeabilities under continuous loading. We observe two-dimensional plane strain finite element analyses instead of ‘real’ soil behavior, and then a back analysis is carried out by use of ‘observed’ displacements. Numerical results are discussed where emphasis is placed upon the interpretation of ‘field measurements’, and we also provide a new procedure of construction control, i. e., control of loading during construction for embankment foundation.

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This study aims to appear isotropic compression characteristic, shearing characteristics and changes of suction in unsaturated cohesive soils by freezing and thawing under undrained conditions. The pore water pressure increases by freezing and thawing and the suction in soils decreases. In isotropic compression, changes of suction in subjected to freezing and thawing soils is greatly. The decrease in the suction is related to the pore formation of soil structure and the decrease in sheare strength.

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In earthquake-proof designing on shield tunnel, the accurate evaluation of the axial stiffness of the tunnel is extremely important. Because the shield tunnel lining consists of many tunnel segments with joints, bolts, and other fasteners, and the inner surface is protected with a secondary lining, evaluation of the stiffness is not simple.
Shearing experiments were carried out on the lining models with different types of isolation. It was found that the shearing characteristic of isolation could for the most part be expressed by Coulomb's criterion.
Further, axial seismic responses of the shield tunnel were analyzed with a new analytical model that allowed for isolation effects and was verified with experimental results. It confirmed the observations that the axial response could be reduced by the insertion of an isolation sheet between the primary and secondary linings.

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Rock foundation permeabilities are affected by many factors like kinds, geological classifications and crack conditions of rocks. Therefore, it is important to examine the relations between the above-mentioned factors and permeabilities in rock foundation. This paper shows the results of the studies over the relations between them by the theory of quantification, based on the observation of the recovered boring cores.

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The permanent displacement of a slope in Noshiro city during the 1983 Nihonkai-Chubu earthquake is simulated by Distinct Element Analysis. The slope of 2.6 degrees average inclination and 200m length is modeled as 3180 element Distinct Element Model (DEM). A FEM model of 611 quadrilateral elements is utilized to verify the DEM model in the small displacement range. In quasi-static analysis using lateral seismic coefficients of 0.1-0.3, both FEM and DEM models are found to give similar failure surface and critical acceleration, i. e., threshold acceleration for initiating failure. Some subsurface layers are supposed to have been liquefied during the earthquake ground motion. In the model, both the stiffness and shearing resistance of these layers are reduced to account for their volumetric change and liquefaction. The movement of the slope due to subsurface soil liquefaction is simulated realistically with the DEM model including vertical crack and settlement at the top of the slope and lateral sliding of the surface layers. From parametric studies, volumetric change of the liquefied layer is found to be the most influential factor to induce deformation of the slope.

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It is generally understood that the most well-known constitutive relations for the overconsolidated clay are based on the theory of isotropic elasticity. When the clay is isotropic linear elastic, the coefficient of the earth pressure at rest is independent of the overconsolidation ratio (OCR). However, most experimental evidences indicate that the value of K₀ varies with OCR.
It is shown that anisotropic elasticity may be considered as one of suitable soil models to predict the horizontal stress of overconsolidated clays. The prediction of the model will be compared with the result of K₀ swelling test.

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The first object of this paper is to modify the method, which was proposed by authors in the previous papery, for determination of parameters of pile bearing capacity formula based on statistical analysis. Accordingly, a new method for estimation of skin friction of steel pipe piles driven into clay layers is proposed based on equation (1). The second object is to show the accuracy of the method. The results of statistical analysis with 68 in-situ loading tests which have been gathered and used in the previous paper are equal to the results of those with 112 tests which are gathered the present paper. Hence, it is seen that the reliability of the statistical analysis by using the data from a sample population of 68 in-situ loading tests is adequate. The new formula is compared with those estimated by the methods currently used in Japan and the engineering usefulness of the new method is emphasized.

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