Study on Stress Characteristics Response of Submarine Shield Segment Under Ultra-high Water Pressure

In the construction and operation stage of shield tunnel, mastering and clarifying the mechanical characteristics of the overall structure is essential for ensuring shield tunnel safety. In this paper, the shell-spring model is established by ABAQUS finite element software for the ultra-high water pressure submarine shield tunnel. The mechanical behavior of shield segment structure under varying water pressure, different key block position and different strata is studied and analyzed. The results show that at the same segment assembly position, the axial force of the segment increases greatly with the increase of water pressure, and the growth rate is as high as 150 %. The internal force of the segment is mainly axial force. Under the ultra-high water pressure, the corresponding position of the maximum deformation of the segment is related to the position of the segment joint at the arch bottom. In the staggered assembly, the axial force fluctuation near the arch bottom is larger than that of the straight assembly, and the peak bending moment and the maximum axial force are near the invert. In addition, near the 120 degree of the vault, the bending moment oscillates obviously near the joint in the stratum with small coefficient of soil reaction. The larger the coefficient of soil reaction is, the more uniform the axial force of the whole segment is. The research results provide a theoretical insights for the optimization design of shield tunnel segments.