Small Spacing Tunnel Parallel To The Three-hole Interaction Analysis And The Stability Of Surrounding Rocks

In order to fulfill the daily increasing transportation demand, the tunnel with more than three cavities which are closely build is more and more popular. However, because of the special structural style, the excavation of different cavities will have interactions on each other, which breeds new problems for the design and construction. Therefore, it is necessary to study on this type of tunnel.Based on the No.1-3 tunnel of Hanfu Mount, which is the tri-tunnel with the characteristics of large-span and small-distance. The article will study on the interaction of cavities and the stability of surrounding rock during the construction of the parallel tri-tunnel. The thesis has mainly completed the following achievements:(1) Introduce the relevant theorems of complex variable in solving the mechanical problem in elasticity plane, and the basic principle of Schwarz alternating method in solving the problem of double connected region.(2) Introduce the application of Schwarz alternating method to the bi-tunnel problem in infinite half plane. Meanwhile, discuss the feasibility of expanding the application to the tri-tunnel problem.(3) According to the idea of "unite cavity" and the theorems of complex variable and Schwarz alternating method, the elastic analytical solution and function for the problem of triple circular tunnels in infinite half plane will be given in the paper.(4) Write a program by Matlab to realize the calculation of the analytical solution, and verify the reliability of the result.(5) Study and discuss the critical interaction distance of the surface deformation and the stress in the shared rock of two cavities, and whose affect factors, such as covering depth, ground loss ratio, elastic modulus and Poisson's ratio.(6) Use the infinite difference software FLAC3D to obtain the strength reduction coefficient of the surrounding rock, and analyze the changing pattern of which under different inter-distance and covering depth. Thus talk about hoe the stability of surrounding rock affected by the covering depth and inter-distance. (7) Research on the trait of the limit damage state of the surrounding rock under different inter-distance and covering depth. The result could be used to analyze the shape of the damage face, the deformation and damage region around tunnel, including the affect caused by inter-distance and covering depth.