During excavation of a large-scale water storage tunnel in soft mudstone, rock deformations at the tunnel side wall have unexpectedly increased corresponding to the stepwise bench excavation. The conventional numerical analysis for designing tunnel supports could not predict such behaviors in advance. In this paper, some different numerical analyses for tunnel excavation in soft rock will be employed as the methods that can reasonably represent such rock mass mechanical behaviors. Analyses of large-scale cavern excavation in soft sedimentary rock will be carried out by them and all analysis results will be compared together with the measurement data in order to improve the prediction of tunnel deformational behaviors.

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The purpose of this study is to investigate the influence of initial static shear stress (ISSS) on cyclic softening of non-plastic silt using volume decrease potential. Through comparing results from cyclic direct simple shear (DSS) tests, it was known for non-plastic silt that (1) although cyclic strength was smaller, cyclic softening of strength was faster, (2) maximum stiffness of non-plastic silt was not smaller than others, but decrement of stiffness with increasing the number of load cycles was more eminent, and the influence of ISSS on stiffness degradation was the largest among them, and (3) liquefaction feasibility of silty soils was explained in terms of the volume decrease potential as well as relative density.

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A method that is proposed by the authors accomplished to reduce the amount of computation to predict the amount of lataral ground flow compared to conventional Finite Element Method by assuming deformation mode of liquefied ground, a definition of potential energy, and modeling the liquefied sand as viscous fluid. The accuracy of the method has been evaluated by some examples of lateral ground flow that was caused by earthquakes. However, evaluation of its accuracy has been impossible in time domain. Therefore, the method is applied to shaking table test on subsidence of embankment and foundations to quantitatively evaluate the accuracy in time domain in this paper, and the existence of reasonable viscosity of the liquefied sand was confirmed.

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This paper describes the results of a frost-heaving model test with anchorage in order to verify the frost-heave-proofing effect of a coned disk spring on the anchor head. The tests were carried out for changing restricted conditions without an anchor, and for changing initial working load condition of anchors with and without a coned disk spring on the anchor head. The following conclusions were obtained. 1) The anchor-working load and the displacement of an anchor plate at the time of frost heave have a hyperbolic relation. 2) A coned disk spring on an anchor head greatly decreased the working load during the frost heaving model test and also improved the anchorage frost heaving resistance. This paper also proposes a method for designing the coned disk spring on the anchor head.

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Recently, people often meet the ground contamination in construction work, and this is large amount and should be treated. It is, therefore, necessary to establish the management scheme of using advection-dispersion numerical method and observation on contaminant behavior. This study deals with how to determine the dispersivity. Since the property becomes larger as observation scale increases, it is difficult to know its value based on real behavior. Several experiments on the behavior led the followings: (1) Flow velocity is dominant, (2) Experimental data nearly fit to document data, and (3) Contaminant plume predicted by using document data is larger than real one.

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The results of the reservoiring simulation of a center-core-type rockfill dam by means of finite element method are reported. Elasto visco-plastic soil/water coupled consolidation analysis using the constitutive equation suggested by Sekiguchi and Ohta was used. The calculated results, change of pore water pressure and the earth pressure during first reservoiring were compared with measured ones, and good agreement was obtained. A tentative plan for the first reservoiring control using this analytical results was suggested and put into practice at an actual dam.

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For using the granulated blast furnace slag (GBF-slag) as an alternative material to marine sand which has been so far used in the ground improvement, the changes of physical properties and permeability of GBF-slag that result from latent hydraulic properties were examined. As a result, it was clarified that the GBF-slag, when used to the sand column without the compaction in the ground improvement method, has characteristics similar to the marine sand column which is installed as the Sand Compaction Pile (SCP) method. Here a design procedure of low replacement SCP method using GBF-slag is proposed and it's validity is confirmed by the newly developed sand-clay composite pile test apparatus.

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A series of centrifuge model tests was carried out in order to investigate the efficiency of chemical grouting as a countermeasure against the liquefaction of sand with existing oil tanks. The test results indicated that the improvement of the area beneath the tank by the chemical grouting was effective in reducing the maximum settlement and differential settlement of the tank and the maximum settlement decreased almost linearly with the depth of the improvement. Some differences were observed in the recorded acceleration and subsidence behavior between 2D plane strain models and 3D models with a circular tank, which clearly showed the 3D effects in the settlement behavior of the tank under seismic loading.

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To prevent large deformation in the Iiyama Tunnel of the Hokuriku Shinkansen, NATM supports were erected twice in succession at the same location. This method is called the Multiplied Tunnel Support System. In this paper, the optimum time interval between construction of the first and second supports was derived analytically by FEM using the estimated creep method. The research reinvestigates analysis using the equivalent elastic modulus of shotcrete. The interval of construction at the site was 12 days, which was very near the ideal interval derived by analysis.

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Some cement treated soils can leach hexavalent chromium, Cr (VI). Leaching tests of samples of previously executed cement treated soils and their surrounding soils have been performed. The results indicate that there is no Cr (VI) detected, even in the soil surrounding cement treated soil in which Cr (VI) is detected. This shows that Cr (VI) is adsorbed or reduced in the surrounding soil. A culum experiment and a batch experiment were done to confirm these effects. The experiments demonstrate that the capacity and strength of adsorption varies with the soil, that the strength of adsorption grows as time passes, and that the emergence of the redox action increases the quantity of Cr (VI) that is captured.

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To study the micro-mechanics of granular flows, two-dimensional rapid flow apparatus is newly designed. Characteristics of this apparatus are as follows; (a) it can deal wide range shear strain rate flows, (b) tangetntial stress can be measured, (c) movement of all particles can be observed by using a high-speed camera.
By using this apparatus, (a) effect of solid fraction on shear stress generation, (b) effect of shear strain rate on the stress generation and (c) relationship between contact pattern between each particles and tangential stress are studied. Contact characteristics between the particles have a much influence on stress generation of the granular shear flows.

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Monitoring the slope displacements can help them assess the stability of the slope. The most important issue when monitoring the slope behavior is how to interpret the behavior and then assess the stability from the monitoring results.
This paper presents a method to detect a sliding plane among many discontinuities for both plane and wedge failures from three-dimensional displacements measured by GPS. The method is extended to predict the collapse time of the slope failure as well as a sliding plane. Both field experiments and numerical simulations are conducted to verify the proposed method.

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In order to apply soilbags to permanent earth reinforcement, the deformation and strength properties of soilbags are studied experimentally and theoretically in this paper. The ways to increase the soilbag/soilbag as well as soilbag/ground frictional resistances are investigated. A set of formulas for predicting the strength and deformation of soilbags with different inclination angles to the externally applied forces are proposed and confirmed by comparing the predicted results with the results of the biaxial compression tests on two-dimensional model soilbags. Based on the deformation and strength properties of soilbags, the design methods for constructing embankments, retaining walls and building foundations with soilbags are established.

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This paper describes the compaction effect of static grouting. The static grouting is utilized as a countermeasure against liquefaction of sandy ground, in which columns of low flowability material, sand or gravel is installed into ground. In this study, a series of model tests on the static grouting was carried out in order to clarify mechanism of compaction by static grouting. Grouting pressure is needed to be increased for expansion of column. However, the results of model tests showed that grouting pressure has an upper limit and that columns expanded without increase of grouting pressure after the pressure had reached the upper limit. Furthermore, it was found that the value of the limit pressure depended on the overburden pressure and initial density of ground. These results and the change of stress state by installing columns are expressed by the theory of cavity expansion.

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In order to clarify the effects of bonding and physical properties of sand particle on one-dimensional compression property of bonded granular geomaterials, a serious of tests was carried out. Four kinds of sands were mixed with a cement agent to prepare the bonded materials. A degree of bonding was varied with cement content and examined from the splitting test. As bonding developed, a compression yield stress increased and a compression curve grew to protrude on the right side of the normal compression line of the non-bonded material. These changes of compression behaviour were attributed to homogenization of microscopic contact load distribution owing to hardening of the cement agent at contact points.

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A series of on-line pseudo-dynamic response tests was conducted to investigate the influence of the degree of consolidation and layer thickness of clay on the earthquake response characteristics of alternating layers of clay and sand. The clay's nonlinear deformation characteristics and their influence on the response of contiguous sand layers were examined. The thickness and configuration of the clay layers were varied to investigate the overall influence of clay layers on the earthquake response characteristics of sand layered with clay. The relationship between the cumulative dissipation energy and the response properties of ground is discussed.

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The purpose of this paper is to propose the grouting material and method for fractured rock masses. So experimental study is executed in order to grasp that the properties of grouting material is stable and impermeable. In this study, experiments of hydraulic test and grouting injection test are performed on bentonite slurry mixes in the laboratory. From the results of the tests, a mixer of ethanol and bentonite is found to be very suitable for a grouting material. Also, dynamic grouting method is able to inject the concentrated bentonite slurry in the fractured aperture.

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Up to now, it has been found experimentally and theoretically that soilbags have extremely high strength. They have already been applied to construct permanent structures. It has been reported from several construction sites that the vibration of the buildings induced by the traffic is reduced greatly after the reinforcement of their ground foundations by soilbags. In this study, a series of experiments were performed to investigate the applicability of using soilbags to reduce environmental vibrations. In general the vibration reduction measures are taken at the place of vibration source, on the propagation path and at the place of vibration reception. The tests were carried out by arranging soilbags with different arrangement in the three differnt places. It is found that soilbags arranged in each of the three places are effective to reduce vibrations.

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This paper describes the effects of geomaterials on unconfined compressive characteristics of foamed mixture lightweight soils, utilizing clay (kaolin clay), silt and coal ash as geomaterials. The effects of geomaterials and curing time on stress-strain behavior of foamed mixture lightweight soils are shown quantitatively. The unconfined compressive strength of foam mixture lightweight soils can be represented as a hyperbolic relationship between unconfined compressive strength and curing time. Several empirical relationships have been also developed. These properties show that coal ash is more effective than clay and silt when used in foamed mixture lightweight soils as a construction material.

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This paper proposes the view of performance requirements of shield tunnel for transmission verified by limit state design method.
First, the design methods on this paper have defined performance requirements of shield tunnel for transmission under every load conditions. Secondly, in ultimate limit states, the beams-springs analysis model and partial factors for shield tunnel have been proposed. Thirdly, we've gotten the adjustments with these design methods and the indexes of the inspections for construction control.

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Based on the concept that the maximum water volume absorbed by unit volume of montmorillonite is constant, the swelling deformation of sand-bentonite mixtures is uniquely characterized using the void ratio of montmorillonite, which is defined by the ratio of water volume to montmorillonite volume. The relationship between the montmorillonite void ratio and overburden pressure at fully swelling is independent of the initial compaction condition and the sand-bentonite mixture ratio, and is a linear line in their log scale. When overburden pressure is large enough and/or the bentonite ratio of the mixture is small, the measured plots deviate from the line. A method for predicting the limited overburden pressure which is linearly correlated with the montmorillonite void ratio is proposed and verified using the concept of the skeleton void ratio.

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On recently deposited ground such as reclaimed land, it has been confirmed that liquefied soils contain finer soils than soils liquefied in alluvial ground. Such fine soils liquefied during previous earthquakes have the following characteristics: they are non-plastic, uniform grain size and low clay content. In such cases, according to the present design specification, liquefaction resistance can be expected to increase with increasing fines content. However, there is no evidence of very strong ground motion at sites where fine soil liquefied. To investigate liquefaction resistance of such fine soils, standard penetration tests and liquefaction tests were performed in a laboratory. The results of these investigations indicated that grain size was not the principal determinant of liquefaction resistance under constant relative density, which was newly defined in this paper, and constant SPT N-values.

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The relation between liquefaction-induced reconsolidation volumetric strain and undrained shear loading history are studied by using hybrid online testing technique. Irregular cyclic shear was applied to clean sand specimen prior to reconsolidation test controlling volume strain rate constant. As a result, it was found that an accumulated shear strain is better index to explain liquefaction-induced reconsolidation volumetric strain. Furthermore, the volumetric strain increases with lower relative density, and larger accumulated shear strain. Finally, based on the tests results, an idealized relationship between reconsolidation volume change and effective stress is proposed.

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Swelling characteristics of Bentonite-Silica Mixture under high temperature are studied experimentally and theoretically. The test results indicate that the swelling characteristics of the Mixture increase with the increase of temperature. The formula proposed by H. Komine estimates overall tendency of the test results. However, “a modified swelling evaluation formula” presented in this paper well estimates the swelling behavior of the Bentonite-Silica Mixture.

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In-situ compaction method is an alternative technology for the construction of a buffer at HLW final disposal. Understanding of the compaction characteristics of the proposed material is important for this method of construction. In this report, paying attention to the relation between compaction energy and the achieved maximum dry density, dynamic compaction characteristic of bentonite and silica sand mixture material is examined.

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Most of irrigation reservoir dams were mostly accumulated with a mud soil in reservoir that caused the pollution and the shortage of reserved water. This mud soil generally is high-water-content and very soft clayey soil. In order to make efficient use of such a problematic soil as embankment soil, we have developed a new type method to repair the damaged embankment by means of the stabilized mud soil with cement stabilizer.
This paper describes the case study of sloping core zone constructed by cement-stabilized muddy soil that applied this method to prevent the leakage of an old small earth dam. It also represents the test results investigated the strength and permeability characteristics of the sloping core zone.

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If PET (Polyethylene Terephthalate) bottles can be effectively utilized as a construction material, the problems of PET bottle disposal and shortage of natural resources for construction may be solved. This paper describes the unconfined compressive characteristics of foamed mixture lightweight soils mixed with flaky PET bottle waste to promote PET bottle recycling. Comparisons are made between foamed mixture lightweight soil and foamed mixture lightweight soil mixed with flaky PET waste. The effects of flaky PET on stress-strain behavior of foamed mixture lightweight soils are quantitatively shown. These properties make flaky PET bottle waste useful as a construction material. The potential use of flaky PET bottles can be refined with further research.

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Mechanical properties of compacted bentonite proposed as one of buffer material for engineering barrier system in high-level radioactive waste disposal were studied by using the laboratory test results. The test results showed that the effective stress concept can be applied to the mechanical behavior of the compacted bentonite. In order to evaluate the applicability of two constitutive models, Sekiguchi-Ohta model and Adachi-Oka model, to the compacted betonite, the models were compared with the test results. Good agreements between the models and the test results were obtained from this comparison.

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This paper describes an improvement and an estimation of the in-situ shear equipment for an accurate testing. This equipment, which is referred to as Borehole torsional shear test (BTST), consists of a shearing part for shearing soils, a pressure control part to apply a vertical stress and a recorder part. First, the place of shear plane was observed to realize the mechanism of shear failure in this test. Second, the effect of the length of a confining ring was examined by comparison with the results from ring shear tests. It is shown that these experimental results from the BTST have a similar tendency with the results from ring shear tests in both constant pressure and constant volume conditions.

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