For the shallow tunnel or the earth tunnnel, the ground water has significant influence on the stability of tunnel face. This report describes about evaluation of tunnel face stability by the rigid plastic finite element analysis (RPFEA) taking account of ground water level. In this report, we represent the effect of the ground water when water pressure is applied as a force on the ground. First, we consider the effect of draw-down of the groundwater level by a non-multi-element model of a two dimensional analysis (2DA). Next, we evaluate the face stability of an actual railway tunnel of Tohoku-Shinkansen by a multi-element model of 2DA.

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A theoretical method is presented in this paper to assess the reinforcing effect of grouted rock bolt for rational tunneling design. Based on the Mohr-Coulomb law and strain-softening behavior of rock mass, the rock bolting effect is evaluated quantitatively considering the interaction ofrock mass, rock bolt and other supporters such as shotcrete. The reinforcing effects of rock bolt in the standard supporting pattern of Japan High Way Accociation have been verified. It is found that the reinforcingeffect of the rock bolt is not significant when it is installed in a relatively weak or very good gound condition. The shotcrete can improve the rock bolting effect in a weak ground condition.

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In this paper, a new practical rock block analysis method for observational design and construction method in large tunnels is suggested, and then applied to the actual example of the large tunnel with a super-large cross-section. The large tunnel is first bored by a 5m diameter Tunnel Boring Machine (TBM) and is enlarged to a main tunnel cross section by New Austrian Tunneling Method (NATM). The suggested analysis method considers finite persistence of discontinuities. To illustrate the applicability of this method for observational design and construction method in large tunnels, theanalysis results are compared and examined with those of the conventional method.

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When excavating a tunnel, earth pressure acting on surrounding ground increase as the overburden load acting on the tunnel is redistributed to the surrounding ground. Though a lot of theories, from Terzaghi's theory down, have been proposed for estimating the magnitude of earth pressure acting on a tunnel, there's almost no method for predicting the distributions of earth pressure around a tunnel. In this study, a method for calculating the earth pressure distributions around a tunnel is proposed. By comparing calculated value with experimental value, it is found that the explained method can be applied for forecasting the earth pressure distributions around a tunnel support system.

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In this study, two-dimensional axisymmetric analysis was made to evaluate the effects of the tunnel round length, rate of excavation and the speed of hardening of shotcrete on ground and support characteristic curves.
As a result, it was found that the production of the strength and stiffness of shotcrete had great impact on ground displacement, that the displacement and stress on shotcreted wall surface varied greatly where the tunnel round length was long, and that displacement was larger than at a point of equilibrium reached under a certain pressure on the support, when the tunnel round length was long in relation to the tunnel diameter.

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We confirmed the prediction of surface settlement with Convergence Confinement Method. It is difficult to measure the antecedence settlement of convergence and crown settlement, which are used as a control point in tunnel excavation. In this investigation, we confirmed the prediction of displacement curve which do not measure antecedence settlement with Convergence Confinement Method.

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Deformational mechanism of an urban NATM tunnel at shallow depth is often characterized by a set of unique kinematic movements in subsidence profile and crown settlement, etc. This paper proposes an improved computational scheme by which characteristic deformation behavior of a shallow tunnel is properly modeled. The new computational procedure, incorporating strain-induced anisotropy and strain softening, was applied to simulate a real shallow tunnel's settlement gradient. The results obtain showed that the new computational scheme could represent the settlement gradient and shear bands developing from tunnel shoulder.

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This report describes to mechanism of cutting face stabilization with Steelpipe Steel-Sheet-Pile Pressfit Blow Method (SSPB) in shallow earth tunnel. This method is a kind of fore polling and is using of steel pipe attached with steel-sheet-pile. The purpose of this method is preventing for loosing degree of adhesion of soil around cutting face. Authores study on the effect of cutting face stabilization of this method using by analysis of 3-D FEM in comparison between fore polling without steel-sheet-pile and fore polling with steel-sheet-pile and research in some measured data of stain about steel-pipe and steel-sheet-pile in actual execution of this method. So, authores confirm that it is an effective method preventing for loosing degree of adhesion of soil around cutting face in shallow earth tunnel.

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During the construction of Inasa No.2 Tunnel on the New Tomei Expressway, both portals, northern starting point and southern ending point, have been subject to large-scale landslides. Based on the obtained knowledge through the construction at the north portal, this paper describes the landslide mechanism caused by tunnel excavation nearby, and the effect of countermeasure against landslide actually implemented in the construction of tunnel.

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Japan Highway Public Corporation (JH) Shizuoka Construction Bureau is now building the Kanaya tunnel in the New Tomei Expressway (New Tomei) in Shizuoka Prefecture. In the mudstone layer where the overburden is deep and competence factor is under 2, excessive internal displacement and foot settlement were observed, together with rock bolt failure and cracks in sprayed concrete. After high tensile strength bolts (748 kN) were introduced instead of rock bolts, displacement was well controlled and strength of the tunnel was enhanced.
This paper describes the characteristics of displacement behavior of a tunnel with large cross sectional area and applications of the high tensile strength bolts as a countermeasure for the displacement, based on the experience of western section of Kanaya Tunnel construction in mudstone layer.

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In this paper, based on the measuring result on axial force of support members (rock bolts and cable bolts) and displacement of tunnel crown and side wall, evaluation on pre-reinforcement effect and support effect of pre-installed cable bolts during enlargement was carried out.
As a result of the examination, following fact clarified. 1) The stability of the ground around the tunnel was improved by axial force arises in pre-installed cable bolts. 2) There is effect of decreasing of crown settlement and convergence in pre-installed cable bolts. 3) It was possible to use the cable bolting system as a supporting member in the main tunnel.

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High quality shotcrete (HQSC) is a new type of shotcrete utilizing own viscosity generated by a mixed powder for the improvement in a construction performance on the tunnel site. Although the viscosity which is the feature of HQSC has been evaluated qualitatively, the quantitative evaluation and the test method to control the viscosity on a construction site has been insufficient. This paper describes the test result of the viscous characteristics, and proposes the index for construction control of HQSC on site.

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As a number of mountain tunnels without reinforcing bars are deformed and cracked by earth pressure, assessment methods of their strength have been researched and established to design countermeasures. On the other hand, there has been no well-established evaluation methods for the structural strength of urban tunnels with reinforcing bars, which are safer against earth pressure. Then, model tests and numerical calculation concerning the tunnels are carried out to investigate the mechanical properties of them. It is confirmed that the tunnels become stable by distributing stress in case of stiffness reduction and their strength can be grasped by using the numerical calculation described in this paper.

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Some tunnels constructed by the conventional excavation method have defects like an insufficient lining thickness and voids behind the lining. It is thought that the structural strength of defective lining becomes lower than that of sound lining against the punching shear stress caused by loosening pressure. Therefore, we performed model tests to quantitatively estimate the influence of initial defect on the structural strength of lining under the punching shear stress. We found that defective lining was brittle in its destructive behavior against the punching shear stress and the structural strength became smaller than that of sound lining when the lining thickness was about half that of sound lining. We proposed a criterion of countermeasures for tunnel lining against punching shear stress based on these tests.

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A practicable method of calculating adjacent structures' settlement by shield tunneling is proposed. First of all, the settlement curve of a transverse direction is obtained by two-dimensional FEM analysis, and the settlement curve of longitudinal direction measured by shield tunneling of similar construction is set. Then a settlement surface is calculated from these two settlement curves. Even if the tunnel route is a curve or the interval between the adjacent structures and the tunnel route changes, we can obtain the adjacent structures' settlement by moving the calculated settlement surface along the tunnel route.

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The achievement of the goals of rational design and safety in a shield tunnel project requires on-site measurement performed to collect information on loads acting on the shield tunnel and stresses and to investigate the mechanism of deformation. There have been few projects, however, for the construction of a shield tunnel in diluvial deposits in which loads acting on the shield tunnel and stresses in the segmental lining were measured over a long period of time. For about 10 years, therefore, on-site measurement has been continued at a railroad tunnel site in the Hongo work area of the subway Nanboku Line in the Tokyo area. This paper reports the results obtained from the 10 years, on-site measurement. The overburden depth at the measurement location is 17.5 m, and the outside diameter of the tunnel is 9.8 m. The lining segments used are made of ductile cast iron and are 1.0 m wide and 350 mm thick. The secondary lining is 150 mm thick.

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Steel fiber reinforced concrete segment is developed in order to improve the quality and to reduce the cost from usual reinforced concrete segment. This paper describes the result of improved bending capacity from the standard proof bending test, measurement result of decreased and even tensile stress distribution of main bar without distribution bar from the bending test with two point loading at outer edge, and the increased bursting capacity of main compression bar without enclosed tie bar from the ultimate compression test with eccentric loading. From these results possibility of reducing main bar quantity and elimination of distribution bar and tie bar is proved.

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This paper describes a method of reflecting the three-dimensional effects in a two-dimensional structural analysis for the design of a rectangular shaft for railway tunnels based on the result of three-dimensional structural analysis for different values of its depth to width ratio. We conclude that in the design of rectangular shaft using two-dimensional structural analysis, the model is divided into the lateral section and longitudinal sections. The two-dimensional frame analysis requires the use of the contributing load based on the Grashof-Rankine equation for the mode in the lateral direction, and the use of the contributing load based on the new equation proposed in this paper for the longitudinal direction.

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The authors suggest that the halved jacking pipe of which the internal diameter is larger than 3.0m has two radial joints on circumference. The joints are arranged at clockwise 45degree by turns. Meanwhile, it is possible for joints to suffer from eccentric loads by pipe deformation due to friction between soil and a pipe. This state is likely to increase if the jacking pipes go forward on curve and meander alignment. Therefore, the joint specification must be determined by analyzing loads distribution to the radial joints. Then the jacking pipe test on the S shaped curve alignment was carried out with halved pipe models. And the test results have led to evaluate section forces to the halved jacking pipes accurately.

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Recently, it has often become necessary to construct tunnels under more severe conditions and to develop new techniques in Japan. However, present design techniques cannot appropriately reflect the construction techniques; and thus, traditional methods are still often used. On account of the well-balanced progress between construction and design in shield tunneling method, an innovation of design technique is required. This paper shows a history of the design method for shield tunnel lining in Japan and discusses objects of research for it.

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