The authors propose the new drilling parameter named “Normalized Drilling Velocity Ratio” for evaluation of geological characteristics ahead of the tunnel face, using conversion analysis of non-core drilling parameters. This newparameter, enable to neglect the change of feed pressure which gives large effect to the rock evaluation, is suitable for rock mass classification and also for detecting of fault zone. We showed the relation between the new drilling parameter and tunnel rock mass classification using tunnel excavation data, and also discussed relations among the parameter, geology, groundwater, deformation, and construction methods.
A sequential excavation analysis was made using an axisymmetric model by varyingthe distance between the tunnel face and the point where shotcrete support was erected as a parameter. As a result, it was found that the point of equilibrium would not be identical with the point of intersection of the support and ground characteristic curves, and that the point of equilibrium on support characteristic curves varied differently near or away from the tunnel face in the case where the distance between tunnel face and shotcrete support was used as a parameter.
The objective of this paper is to clarify the effect of inner reinforcement, such as inner concrete lining, carbon fiber sheet reinforcement, steel support and steel plate reinforcement, on the restoration of the load bearing capacity of damaged concrete lining. In this study, model experiments using full-scale concrete lining specimens were carried out and new knowledge about the effect of inner reinforcement was obtained. The results show that the effect of inner reinforcement depends on the type of inner reinforcement and characteristics of failure. Furthermore, the results show that there is a limit on the effect of inner reinforcement unless damaged concrete lining itself has sufficient load bearing capacity.
Shield-driven tunneling method hereafter will be adopted in deep underground. In deep underground, while the earth pressure is lower because of the ground being more stable, the water pressure is higher. The the small earth pressure makes bending moment small but high water pressure makes the axial force large in the segmental lining. Therefore, using steel segments as the lining, there is high possibility that the local buckling of main girder of steel segments will occur. In this paper, the behavior of the local buckling at main girder of steel segments is studied by the test results using the modeled specimens and by the results of numerical analysis using the Finite Element Method. As a result of this study, the numerical analysis explained well the test results.
In large cities in Japan, as the shallow underground is extremely complex use nowadays, we need to construct new infra-structures in deeper underground. Water pipelines are not exceptional. In deep underground, the water pressure exceeds, the buckling of steel water pipes is a considerable problem. To prevent the buckling, it is necessary to study the mechanism of its buckling behavior for the design of such pipelines. In this paper, the buckling behavior is mentioned from model tests using aluminum seamless cylindrical pipe with water pressure. The result of the experiment is compared with the analytical results by FEM, then the behavior of buckling is discussed.
Damage on segment during excavation at sharp curve due to construction loads gives heavy influence to tunnel durability. But these mechanism have not yet been made clear quantitatively. In this paper, at first, the contact force between shield tail and segment was calculated by the modified kinematic shield model with shield-segment interaction in detail. Using the measured jack force and the obtained contact force, the segment displacement was analyzed by 3D segment model with a ground reaction curve. Finally, the performance of its model was discussed, comparing the obtained segment displacement with the measured one.
In this research, at first, the behavior of a diaphragm wall and reinforcement wall of shield tunnel entrance of a deep circular shaft was examined using a field measurement data about past underground river project in Tokyo. The data involved at the stages from diaphragm wall construction to shield tunnel construction. Next, three-dimensional total stress elasto FEM analysis was conducted to examine bending moment and axis force of the diaphragm wall. As a result, understanding a detailed movement of the shaft required the effective stress analysis that could consider the behavior of controlled underground water while the process of soil excavation within the diaphragm wall.
Tokyo Metro Co., Ltd. constructed the No.13 subway line 8.9km long between Ikebukuro and Shibuya, and it was open for traffic in this June. This line's deepest point is between Zoshigaya station and Nishi-Waseda station, so we constructed a pumping station which was located at a crossing with heavy traffic and was at a depth of 33m with high water pressure. Considering these conditions, we chose a non-open construction of a pumping station by PSS-Arch Method. This paper shows and argues about the results of measurements of segments, curved steel pipes and support structures, and confirms an assumption obtained from measurements by 2D-FEM.
We propose a new numerical analysis method which combines beam-spring model and discrete element method. This method enables stability analysis of tunnel lining with large deformation or change of analysis domain. Analysis of a box culvert is solved as an example of this method by using the program which is based on the formulation explained in this paper.