Geo-space is a general term used here for earth-integrated spaces at different depths and in different forms. The term is also commonly employed in Japan for space to be created deep below ground. The Japanese designers have recently introduced several innovative concepts on the usage of such deep geo-space especially for diverse infrastructure and have integrated within it the use of a “shallower” geo-space for daily multi-human activities. This paper is concerned with the shallow below-ground zone of around ten meters depth. It discusses the correlation between the thermal performance and the design form, the functions and the significant benefits of such geo-space.

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Dense sands, overconsolidated clays and soft rocks show strain-hardening and strain-softeing behavior in a certain range of confining pressure. The aim of the present paper is to construct a constitutive model of soft rocks that can describe not only strain-hardening but also strain-softening behavior. The constitutive model is derived by introducing a stress history tensor. The derived constitutive model is examined by comparison of the calculated results with experimental results of sedimentary soft rock (porous tuff). In addition, the applicability of the model to numerical analyses is discussed in relation to the uniqueness of the solution in an initial and boundary value problem.

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In order to investigate the fundamental mechanism of gas seepage in rocks and open-cracks, the experiments were carried out by using three inherent apparatuses. This paper presents how to determine the intrinsic permeability of rocks having one-dimensional and axisymmetric seepage flow in a laboratory. Some characteristics of gas flow in rocks and open-cracks were discussed based on the experiments and the calculations. The rock intrinsic permeabilities were in the range of 10^-19-10^-15m² to various kinds of rocks. The leakage condition of gas in open-cracks could be obtained. Namely, it is relationship between P_G/P_W (P_G: gas pressure, P_W: water pressure) and crack width as a parameter of P_W.

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Fine cement particle injection method was invented for the purpose of grouting the ground with low permeability where had not been improved by conventional cement milk grouting. This method aims at injecting fine cement particles into the ground or bedrock together with air in an aerosol state.
In this paper, we describe that the powder grouting method is based mainly on the phenomenon of reentrainment of the fine particles caused by increase of actual air velocity due to narrow space of pores in the ground which is filled up with them, and show that the reentrainment velocity of surface improved cement is about 0.1 to 0.4 meters per second.

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In order to obtain a model predicting liquefaction potential in a wide area, the analyses based on Quantification Theory II were applied for the liquefied and unliquefied areas in Nagoya during the Tonankai earthquake (1944, M=8.0) by using the several items which were related to liquefaction. As a result, the author obtained a model which made a discrimination between the actual liquefied and unliquefied sites at the rate of 80%. The items used for this model, arranged in order of degree of influence on liquefaction, are thickness of saturated sand layer, topography, depth of groundwater level, thickness of clay and silt layers, seismic coefficient, and STP N value. The author tried to evaluate the liquefaction potential for the alluvial ground in Nagoya during the predicted Tokai earthquake by using this model and showed the dangerous regions which had high liquefaction potential.

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Mechanical properties of brittle materials, such as concrete and rocks, are greatly depend on the microstructures induced in the process of deformation. Thus, it is important to take into account the evolution of microstructures in the formulation of constitutive equations for brittle materials. In this paper, the concept of crack tensor is introduced to represent the effect of microcracks on the elastic properties of brittle materials. Then a criterion for the evolution of microcracks is proposed and an applied result is compared with a test result on rocks. Finally, the applicability of this criterion to the constitutive model with strain-softening is discussed.

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In this paper, a new technique of estimating the layer structure and contents of clay minerals are proposed by paying attention to the relationship between the moisture characteristics of the clay minerals and heating temperature.
The moisture contents of the standard specimens made by mixing Monmorillontite, Kaolinite and Quartz in various proportions were measured based on the weight loss with heating.
The results are summarized as follows: 1) The applicability of ignition loss test was recognized based on the results of differential thermal analysis test. 2) The dehydration of constitution water occured at 530°C in two layer clay mineral and at 800°C in three layer clay mineral.

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In the case of low temperature materials storage, such as LNG, LPG and frozen food etc., in opening excavated in mountain, as the cracks around opening will be developing with time by shrinking the opening towards against mountain, leakage of liquid and cold air from the cracks become important problem.
In this study, the authors proposing “water curtain system”, which the way enclose the liquid and gas with water in mountain. Moreover, proposing “ice lining system”, which the way set up the layer of ice inside of opening.
And then, the results which the effect on these systems were confirmed by experiment and analysis are described.

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Several conventional formulas are proposed for estimating earth pressure induced at a shield tunnel cutting face and friction resistance induced around a shield during shield thrusting. However, the validity of them are not yet clarified due to lack of field observed data for comparison. The authors collected field observed data of the earth pressure and the friction resistance as to 22 shield tunnels excavated by mud pressure balanced shield. Basing on the data, they investigated on actual earth pressure at rest at a cutting face and actual friction resistance around a shield and compared them with values calculated by the conventional formulas.

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In estimating the bearing capacity of the friction pile, it is important to improve the reliability of the bearing capacity formula. The uncertainty in bearing capacity of piles exists in estimation of both parameters on bearing capacity coefficients and soil properties. To increase the reliability of bearing capacity of piles, knowlegdes obtained from in-situ vertical loading tests of piles must be applied to prediction of actual piles. Besides, it is necessary to know the spatial variation of soil properties used for estimating the pile capacity on the basis of field investigation. In the present paper, by directing an attention to the bearing capacity of cast-in-place concrete piles, the authors present a method for evaluating the reliability of bearing capacity of viaducts founded on friction piles with consideration of the results from vertical loading tests and the spatial variation of soil properties.

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Cyclic loading tests of the pre-stressed rock were conducted in order to estimate the pre-stress of the rocks. In these tests 4 AE sensors were used to determine the hypocenters. The results showed that the shorter the elapsed time after the applied pre-stress loading, the clearer the Kaiser effect. With the increase of the elapsed time, however, the Kaiser effect became less clear. But, in that case, the rapid AE increase appeared at the pre-stress point on and after the second loading. Therefore, it was possible to estimate the pre-stress even when the Kaiser effect was not observed clearly in the first loading. We suggestthe pre-stress estimation method using the AE characteristics in cyclic loading. According to the suggested method, we could estimate the pre-stress with the average error of 1.5% for the elapsed time range of 1 hour to 400 days.

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To clarify the size effect of track belt on tractive performance of several bulldozers running weak silty loam terrain, the variations of terrain-track system constants due to the size of track model have been investigated experimentally. And then, the tractive performances of bulldozer having several sizes and weights have been analysed by use of rigorous simulation program. As the results, the shear resistance of soil on the interface between track and terrain decreases with the increment of track size and the amounts of static and slippage sinkage increases with the size. And it is clarified that as the size effect of track belt on the tractive coefficient and the tractive efficiency of power of bulldozer running weak cohesive terrain occurs remarkably, this problem should be considered carefully to estimate the true tractive performance of bulldozer.

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The evaluation process of cut-off slope stability is an ambiguous system which is made up of ideas subjected to practical experiences of an expert. This evaluation system uses the possibility linear concept of fuzzy theory together with the basic data from actual cases of slope failures during and after construction. In this research the input data for evaluation ranking is obtained from the values of the slope-evaluation table showing the results of subjective and qualitative analyses of experts. The failure pattern is taken as an external mode of standard. And the slope failure after construction is predicted on the basis of the adopted system during construction. This fuzzy system clearly defines the problematic differences in nature upon prediction of slope-failure possibility factors during and after construction.

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It is important to evaluate the compaction characteristics of submerged sand since the quality of compacted sea bed is much influenced by the compaction methods. However, there are only a few studies concerning the compaction of submerged sand. The aim of this paper is therefore to make clear the basic mechanism of the compaction of submerged sand. Some factors including rammer weight, rammer dropping height and number of rammer drops etc. are experimentally scrutinized by use of conventional Proctor compaction apparatus. A series of tests using air-dried sand is conducted to compare with the properties of submerged sand.

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In order to investigate that a triaxial chamber can be used to measure the permeability of borehole samples obtained from the deep underground, a series of permeability tests in triaxial cell was performed on reconsutituted sand samples and boreholes samples. Test results indicate that the method in this study seems to be suitable to measue the permeabilities of vertical and horizontal directions of borehole samples.

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A series of consolidated undrained triaxial extension tests using remolded samples of two kinds of clays was performed to investigate the influence of specimen size on undrained shear behaviour of clays.
The height to diameter ratio of specimen was changed from 0.5 to 2.4. Triaxial test specimens were consolidated isotropically without lateral filter paper drain and then sheared under undrained extension by decreasing axial stress, while lateral stress was maintained constant.
Based on the test results, it is suggested that the suitable height to diameter ratio of the specimen for tnaxal extension test is around unity.

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Mercury intrusion porosimeter is one of the most effective method to measure pore size distribution of porous materials, such as concrete, ceramic, rock, activated carbon, etc. The application to soils is limited to clay or sandy-clay, because desaturation destroys the soil fablic and makes the pore geometry and structure change. This technical note addresses to a new technique for the preparation of sand specimen for the mercury intrusion porosimetry. It uses no special substances like Kaolin or resin for bonding the sand grains together. Therefore, the measurment offers an exact value of the pores being formed by sand only. Void ratio, which is one of macroscopic features of soil pore, is checked in details for making sure of the efficiency of this method.

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