Numerical Simulation And Model Test For Effects Of Close-Spaced Construction Of Subway Shield Tunnels

Along with the development of the subway construction and the extensive utilization of the shield tunnel technology, researches of the influencing rules in the closed-spaced shield tunnels and the corresponding control measures become to be an exigent problem. Based on the Guangzhou Metro Line No.3, close-spaced section shield tunnel, this paper uses FEM and similar model test as the research means to systematically study the influencing rules among the under construction tunnels and existing tunnels, by studying on three instances of the close-spaced shield tunnel: right and left parallel,up and down crossed,up and down perpendicular.Main Research Methods and Contents:1. Theoretically analyzing the displacement and stress transformation character in existing tunnels, which are caused by the construction of newbuilt tunnel, and simplifying shield tunnel as the homogeneous cylinder according to the equivalent rigidity, so as to set the foundation for the following FEM analysis and model test.2. Adopting FEM to carry out 3D numerical analysis to simulate the close-spaced shield tunnel's construction mechanical behaviors, and analyzing the displacement and stress character in the existing tunnels, which are influenced by the stress release and Pipe-jacking Force during the construction.3. Taking geometric similarity ratio C_l=40 and bulk density similarity ratio C_r=1 as basic similarity ratio to carry out model test. Changing the Pipe-jacking force during the construction to achieve the displacement and stress transformation rules in the existing tunnels.4. According to the results of FEM analysis and model test, summarizing the construction measures in the close-spaced shield tunnels and the control measures in the course of constructing in difficult and special areas. Offering several references in the construction of closed-spaced shield tunnels.Main Research Findings:1. Analyzing and comparing the influences to existing tunnels by the stress release and Pipe-jacking Force. Putting forward that the stress release is the main factor to influent the existing tunnels.2. Analyzing the size of influence and influence area during the construction. Using the model test to analyze the influence rules of the Pipe-jacking Force.3. According to the size of influence and influence area in the existing tunnel caused by the construction of newbuilt shield tunnel, put forward the corresponding control measures during the construction.