Shirasu which is defined as the non-welded part of pyroclastic flow deposits is widely distributed in the southern part of Kyushu Island. Shirasu is regarded as soft ground when the mountain tunneling method is applied because its unconfined compression strength is about 50 kN/m². Nevertheless, it is well known that Shirasu tunnels are comparatively stable. In order to make this mechanism clean, we have already proposed a numerical analysis method considering geotechnical nonlinear properties of Shirasu ground. In this paper, we adopted this method to a tunnel with an extremely large section in Shirasu ground and confirmed the validity of this method by comparing the numerical results with those obtained from the field measurement. Further, we analyzed the peculiar behavior of the tunnel with the extremely large section.

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 For tunnel construction, back analysis is used as an evaluation technique of ground and support member behavior. This method is an effective design tool in the clarification of the mechanism, examination of reinforcement method and the examination of the construction method, because that can represent the behavior of ground and support members in more detail and quantitatively.
 In this study, the relatively simple back analysis method, which combined Particle Swarm Optimization:PSO and the finite difference method, was adopted to presume the ground material properties of the nonlinear constitutive equation and the initial stress of the ground at the same time.
 This paper reports on the validation and the issue of the method by the numerical simulation.

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 During the construction of the Tohoku and the Hokuriku Bullet Train lines, several shallow tunnels were excavated in unconsolidated grounds using the New Austrian Tunnelling Method (NATM). In order to prevent settlements of ground tunnel and to ensure the stabilization of the cutting face of the tunnels, ground improvement was carried out in the above-mentioned fields. In the construction areas where the aboveground parts were unrestricted, the ground around the tunnels was improved by mixing in cement before the tunnel excavations; and thereafter, the tunnels were excavated using NATM. Various combinations of improved areas and levels of strength were tried in the fields, and the tunnels were excavated successfully. However, the mechanism of the effect of the ground improvement method and the influence of the improved strength, depth and width of the improved areas are not clearly understood.
 In this study, 2D elasto-plastic finite element analyses are carried out to clarify the mechanism of the ground improvement method. The results of the numerical studies indicate that the ground improvement method used here can effectively prevent the settlement of the ground, as well as the settlement of the crown and the foot to the tunnel, by reinforcing the ground around the tunnel, and that the method becomes even more effective when the width of the improved areas are increased.

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 In grouting the openings behind the lining of mountain tunnels. there are two subjects for efficiently and safety work. You need a quantitative evaluation of the influence of the openings behind the lining on seismic performance and you need the appropriate construction method of the grouting. On this study we examined the influence of the range of the openings and the lack of the lining thickness on the seismic performance. And next, we measure the injection pressure acting on the lining by experiment, and we examined the appropriate construction method of the grouting by numerical analysis using the results of the experiment. Then, in the opening's range of 60 degrees to 90 degrees, loss of seismic performance is remarkable, and the strength is further reduced by the lack of the thickness of the lining. And last, in the case of the thickness is thinner than designed, here is a possibility that lining is destroyed by the injection pressure. but it is possible to low the injection pressure acting on the lining by shorting the arrangement pitch of the pipes for grouting.

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 Recently, owing to the development of tunnel support and reinforcement techniques, the NATM has been increasingly used even for large section tunnels, squeezing tunnels and shallow tunnels in urban areas. Therefore, the authors have focused on quality improvement of rock bolting and developed the diagnostic technique of installation condition of rock bolt using ultrasonic wave, the high friction anchored rock bolt using checkered steel pipe and the simplified axial force measurement device using LEC(Light Emitting Converter). This paper presents that the details of each development and the actual employment of these new techniques to several site.

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 Some mountain tunnels suffered from ground heaving require some countermeasures in service, but these designs often depend on empirical methods. Therefore, reasonable countermeasures against heaving become a significant problem. In this study, swelling is focused on as the mechanism of ground heaving, and the model experiment and numerical analysis that express swelling are carried out. As the result, the model test can simulate the heaving phenomenon which progress as time goes on, and it is confirmed that downward rock bolts curb the heaving by the effect of stiffness improvement of tunnel structure. Additionally, the effect of downward rock bolts specifications such as the number of bolts, their diameter, length and the value of prestress are estimated quantitatively.

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 We report the prediction method about the structure borne sound in the outdoors and the inside due to blasting vibration. In addition, the results of the prediction method were compared with measurements in a tunnel construction site.
 Based on a measurement example of vibration level and noise level in the plural tunnel construction spots, We grasped the characteristic of the sturucture born sound due to blasting vibration.

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 In this paper propose, a methodology to identify the Markovian transition probability matrix, which is presented to forecast the degradation process of cold region tunnel lining for performance based design. Reliability, effect of rehabilitation, and steady state probability of tunnel linings, can be evaluated by this process. The degradation states of the tunnel linings are categorized into several ranks, and their degradation processes are characterized by the tunnel management system. The Markovian transition probability matrix of the degradation states which are defined for fix intervals between the inspection points in time. And, Markovian transition probability matrix have to carry out conversion to a discrete value from a continuation value of tunnel lining degradation. The applicability of the identification methodology is investigated by the inspection data set of tunnel linings in Hokkaido.

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 To prevent a piece of lining concrete from falling is important issue in the maintenance of railway tunnel. It may be effective to quantitatively monitor the strain of lining, deformation of tunnel section, crack width and others. However, this kind of monitoring method cannot estimate the progress of defectiveness, such as the progress of cracks, when the progress occurs at the deep part of lining. Therefore, this paper proposes the monitoring method by means of train-induced vibration, focusing on the change of characteristic of vibration on the tunnel lining and investigates its applicability by means of the measurement of train-induced vibration inside a railway tunnel and the model test with beam specimen.

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 A large number of tunnels in the world have been in service for several decades, and their health conditions deteriorate with the increasing service ages. Therefore, effective inspection methods are essential to accurately assess the health conditions of tunnels. Visual inspection method has been commonly utilized to investigate the integrity of lining concrete, however, this method is incapable of providing sufficient information about the inner state of the lining concrete, such as the existence of cracks and cavities. Since the microtremor characteristics of a concrete structure are significantly affected by its damage degree, this feature may serve as an effective method to investigate the health condition of a lining concrete. In this study, in-situ microtremor measurements were conducted on three spans of a road tunnel with varying damage degrees, and the power spectra density of the microtremors were analyzed. Then the microtremor behavior of the tunnel lining was simulated by using the two-dimensional finite difference code of FLAC. The results of both field measurements and numerical simulations indicate that the ratio of power spectrum density(RPSD) in the range of 0-110 Hz, can be used as a indicator for the damage location, type and degree. For the damaged lining where voids exist, the RPSD values are smaller than 0; for the circumferential cracks, the RPSD values are larger than 0. Therefore, as an initial step, this study gives clear evidence that the microtremor intensity characteristics have strong relation with the health conditions of lining concrete, which has the potential to be used in engineering practices.

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 This paper describes design of segment about jack thrust by the construction load of sharp angle curve shield tunnel. In recent years, the shield tunnel has become sharp angle curve radius of curvature of less than 30m. In this case, eccentricity of the jack thrust, the design of segment, it is necessary to measure the attention to buckling. Accordingly, it is intended that the safety was confirmed based on the results of the jack thrust test and measurement eccentricity.

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 In this paper, we report on experimental evaluation of the concrete plate reinforced by grid FFU (Glass Fiber Reinforced Urethane) subject to distributed load. First, to clarify the bearing capacity of a simply-supported composite beam of concrete and FFU subject to bending moment, bending tests were carried out. As a result, the bearing capacity of the composite beam almost agree with that obtained by the fiber method, when concrete and FFU is integrated. Then we conduct the bending tests on the mortar plate reinforced by grid FFU, subject to distributed load. Consequently, it is found that the bearing capacity of the plate may depend on the mechanical kinematics associated with cracks and increases of bearing capacity can be expected because of confinement effect of grid FFU. Finally it can be said that the concrete pate reinforced by grid FFU embedded in RC walls has more bearing capacity than that calculated by yielding line theory as well as plate theory.

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 In new projects at great depths, the ratio of the construction cost of a shaft to the total project cost has been increasing. However, because no specific design method has been established, the method for small- and medium-depth projects has been applied to temporary diaphragm walls for great-depth circular shafts. In these circumstances, the design load has been determined without sound scientific reasons. In the study presented in this paper, working earth pressures were estimated from stress resultant in the direction of the horizontal section of diaphragm wall, calculated using measurement data, and the estimated earth pressures were simulated by FEM analysis considering initial plastic deformation, to review the method of setting earth pressure in the design of diaphragm walls of great-depth circular shafts. As a result, the earth pressure coefficient was set at about 0.2, which ensures stability of the ground at great depths. In addition, this paper summarizes the concept of the method for setting design earth pressures as a function of the N value.

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 This paper shows a model test of the reinforcement method using the ground solidification body and its FEM analyses that were conducted to examine deformation characteristics of the reinforced underground structure and the effect of the reinforcement. The effect of the reinforcement was confirmed by comparing the results of the loading tests with the reinforcement and without it. And elasto-plastic FEM analyses could reproduce the behaviors of the underground structure in the loading test. Furthermore, with the elasto-plastic FEM analysis used for the numerical simulation of the loading test, seismic response analysis for the full-scale structure was carried out in order to confirm the effect of the reinforcement.

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