In the rational tunnel support design, numerical analysis is a powerful tool to know the estimation of the behavior before tunnel construction. In order to evaluate the support structure quantitatively, it is necessary to understand the effect of the inhomogeneity of rock mass to the tunnel support stress in advance. In this study, tunnel excavation analysis considering the inhomogeneity of rock mass was carried out. The analysis results were compared with the stress measured in the tunnel support in the Horonobe underground research laboratory. As a result, it was revealed that the local stress measured in the tunnel support can be simulated by considering the inhomogeneity of rock mass stochastically.

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 It is known that the controled blasting with continuous slot can largely reduce blasting vibration. However, the mechanism of its effect has not been discussed yet. Therefore, the design of the rational blasting pattern in the controled blasting with continuous slot was difficult to be realized.
 In this study, the vibration reduction due to the employment of the controlled blasting with continuous slot is discussed from the viewpoints of the fracture behavior, the energy balance in the neighborhood of blasthole and the wave energy radiated to the far field. To this end, numerical experiments are achieved, and the role of free face and the dynamic nature of radiated waves are investigated.

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 The purpose of this report is to study on measurement and evaluation methods of exactly obtaining sound pressure at blasting excavation in tunnel mines and to obtain knowledge for improving the accuracy of the prediction formula of blasting noise/low-frequency sound propagation. Thus, a measurement method and an evaluation method of separating measurement data of sound pressure in tunnel mines into incident waves (blasting sound pressure from a working face) and reflected waves (reflection from a door or an opening) are proposed. Furthermore, the validity of the evaluation method of measurement data was examined using model experiments. This evaluation method was applied to measurement data obtained at the blasting excavation site. Finally, the new information obtained was summarized.

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 In the construction of the invert concrete, a section of the lining concrete experiences cracks caused by temperature contraction caused by the cement heat of hydration and the fluctuations of the outer temperature. The creation of these cracks affects durability. For this reason, in order to minimize the creation of these cracks, the authors proposed the “Localized Pipe Cooling” method. This method consists of placing cooling pipes only in the parts of the lining concrete experiencing high tensile stress. In the particular case of this study, the cooling pipes were placed in the lower-center part of the lining concrete. To confirm the mechanism of this method, three-dimensional FEM thermal stress analysis was performed.
 The localized pipe cooling method was applied to a real tunnel under construction. The application of this method was able to prevent the outbreak of penetration cracks. As a follow-up analysis, the authors measured the inner temperature and restriction distortion measured in blocks 1 to 4 of the concrete lining, confirming that the crack-outbrake probability dropped by more than 20%.

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 By the collapse of ceiling panels in Sasago tunnel and the collapse of lump in Uri tunnel in 2015, it turn out completely inevitable the falling of the appendage by periodic inspection.
 This research proposed the sensing method which aimed at a lump among the road tunnel appendage and utilized sensor by MEMS (Micro Electro Mechanical Systems) technology.
 Moreover it was based on the past study which inspected practicality, and the proposition as the tunnel preservation monitoring system which made an experiment as well as put practical use in the view to inspect the problem which is at the time of the past study was performed.

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 To consider the effect of the void on the tunnel lining, three-dimensional behavior of a cylindrical tunnel with a void behind the lining under isotropic compression and sher loading are theoretically analyzed. Numerical results show that the presence of a void causes a negative effect to the lining associated with the change of the stress state of the lining from the axial thrust to bending moment. The tensile stress caused by the void can occur in the inner lining when the void length in the longitudinal tunnel direction is longer than the tunnel radius. Effect of the void on the lining increase proportional to the void length in the longitudinal tunnel direction, and the upper limit of the length strongly depend on the void length in the circumferential direction.

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 Determining the cause of cracks in tunnel linings is important to establish an efficient repair scheme. This study addresses the use of the lining shape obtained using laser scanning for the investigation of the cause of cracks. A tunnel constructed by timbering support method was selected and considered to not be affected by any external force. Profiles of the tunnel lining were measured using a mobile laser scanner with improved accuracy. Curvature radii of the upper section of the tunnel lining were then determined by the proposed method using the three-dimensional point cloud obtained from the laser scanning results. The results showed the characteristic distribution of the curvature radii that were consistent throughout each installation interval of assembly form centering. It is difficult to consider that the distribution of the lining shape resulted from the deformation of the lining owing to an external force in the case when this type of distribution is observed. It is, therefore, concluded that the cracks in the lining were attributed to causes other than an external force, such as deformation of the concrete lining during the curing process.

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 The objective of the study is to measure the displacement of the crack by using a digital camera image. In this measurement technique proposed here, the reflective targets are installed at the measurement point around the crack as gauges and the digital image of reflective targets is subjected to process which consists of image processing and photogrammetry, and the two dimensional displacement of the crack is calculated based on the coordinates of reflective targets. In this paper, experiments were performed to verify the accuracy and precision of the measurement. This paper also showed the actual tunnel measurement results to demonstrate that the cracks on the tunnel wall by using this method.

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 In some cases, the long term heaving occurred at mountain tunnels after construction, despite having invert arch. As a countermeasure, we proposed the flow to inhibit the long term heaving that indicate invert arch structure as to geological condition and convergence and it applied to all mountain tunnels that under construction since 2014. But currently, there are a few cases that apply to the flow, and there is a small amount of data to check the effect of the flow. In this paper, we make numerical analysis model that can simulate heaving for real. And we analyze by using the model and considering invert structure, invert support, early closure as parameters to verify the inhibitory effect against long term heaving.

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 At a shield tunnel constructed in a soft ground, a severe case , that the inner space of the tunnel is reducing by the decrease of rigidity of a segment which suffers from salt damage and increasing ground load, is found. One of the ways to reinforce such a tunnel is to increase the rigidity of shield tunnel lining by constructing pillars in the tunnel. For designing the pillars, however, it is necessary to predict how much the rigidity of the segment could weaken and to make a model for a composite structure of segments and pillars. In this paper , it is discussed that the statistic estimation of remaining amount of main iron members at a shield tunnel suffering from salt damage. Moreover, how to reflect the model based on the statistic result to the design of pillars is discussed.

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 FEM is adopted to analyze the behavior of twin tunnels located closely less than 0.5D. Generally FEM analysis for tunnels at the completion stage has been done, not at the construction stage. Therefore, this study tries to simulate numerically the influence of face pressure and grouting pressure at the second shield construction, and the stability of the first tunnel by inverse analysis with the monitoring data at the actual tunnel project. Then it is aimed to introduce a new numerical parameter which enables simple design method without FEM analysis. This paper describes the monitoring result at the site and the process of analysis to calculate the parameter.

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 In recent years, many shield tunnels with shallow overburden have been constructed for the purpose of cost reduction in construction of vertical shafts. Such shield tunnels are constructed in soft ground, they are strongly affected by earthquake.
 In this article, a composite segment employed at a construction site of Keiyo-Junction is picked out as an example for an analysis, and the result based on the demostration experiment of segment joints, are described. By performing demonstration experiments and an analysis, the load-bearing mechanism and fructure behavior of segment joints which are subject to high tensile force are shown, and the method and result for reinforcement of such segment joints are considered. Also, impact of rotational spring of segment joints is examined.

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 This research carries out model tests to investigate the behavior of multi-section cut-and-cover subway tunnels with the shear displacement of surrounding ground caused by seismic motion, which has not been fully investigated. A multi-section model tunnel as well as a general box type one is installed in a soil vessel and it is found that the sectional force corresponds to those obtained by tunnel design. Then, shear displacement is applied to the model ground and the test results show that the bending moment and shear force are comparatively large in the center wall, the tendency is different among the loading direction and the model tunnels are deformed according to the shear deformation of model ground.

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 This study proposes a tunnel roof support structure formed by interconnected steel pipes for use in the planned enlarged tunnel sections of the Tokyo Outer Ring Road and evaluates the feasibility of such a tunnel support structure. The design of the structure expects the soil between adjacent steel pipes to bear axial force. The load-bearing capacity of the connected pipe roof structure is affected by the outward confinement provided by the tunnel and ground improvement. In this study, a full-scale compressive loading test was conducted to investigate the effects of bolt confinement and ground improvement on the load-bearing capacity of the connected pipe roof structure against axial force.

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 Strain generated during freight train passing was measured in box culvert composed of steel elements jointed by bitten joints built by non-open cut method as under-track crossing structure. Three dimensional FEM analysis results of the measured value verified that calculation conditions of train load considered during design does not match the measuredstructure. By conducting structural analysis using design load and measured load, we verified the difference of generated section force due to the difference of train load calculation conditions, and confirmed that under-track crossing structures designed by the current criteria was evaluated sufficiently on the safe side.

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 Underpass tunnels are often constructed under shallow earth coverings by either the method of combination of temporary elements or the method of replace elements with box culvert. For the latter method, the interaction between the pipes, grounds and box culvert have not studied yet. In this study, to construct underpass tunnels safely, a method of settlement prediction and the countermeasure of decreasing track displacements are developed. In this paper, several simulations of the construction of underpasses are conducted by the method of prediction, then the usability of the countermeasure were confirmed by modeling tests of soil layer. Finally, the results of the field application tests are shown in the actual construction site.

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[in Japanese]

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