Three dimensional numerical lining damage analysis under pore pressures 3D finite element model
Segment is the basic structure unit of a shield tunnel. Lining is the main part of the segment. The mechanical behavior of the lining affects the form of reinforcement, the ratio of reinforcement and the cost of whole tunnel. Therefore, it is significant to clarify the mechanical behavior of lining in construction stage under pore pressures, which can save the engineering investment and optimize the segment design. Foregoing researches (Blom et al., 1999; Nomoto et al., 1999; Sramoon and Sugimoto, 2002 Koyama, 2003; Kasper and Meschke, 2004) seldom involve the mechanical behav-ior of segment lining. At present, the methods of research on segment lining are mostly limited in the indoor full size experiments plus some field measurements. Zhang et al. (2002) tested the lin-ing stress of segment joints through indoor experiments. Chen et al. (2004) performed a field measurement on one section of shield tunnel in Guangzhou Metro and researched the property of lining in different work conditions. Dobashi et al. (2004) researched the rational design of steel segmental lining in Central Circular Route. Due to the various types of loads and the complicated boundary conditions, it is very difficult to simulate the actual loads and boundary conditions in indoor experiment. If the loads and boundary conditions are not precisely simulated, the lining stress measured indoors may have rather large errors. Field measurement may be quite precise for lining stress. However, for different tunnels, the limited test results cannot reflect the whole picture of their lining’s mechanical behavior under different construction and geological conditions. In this paper, a load-structure theory was applied. A finite element (FE) program of ADINA was adopted to establish a 3D numerical model for the shield tunnel. In order to simulate the actual situation precisely, key segment and tail of shield machine were considered. The lining stresses in the normal construction stage and under pore pressures were analyzed.