Analysis on impacts of dual-line rectangular pipe jacking over-crossing construction on metro shield tunnels
Insufficient understanding of the structural forces and deformations of shield tunnels under the influence of new dual-line rectangular pipe jacking over-crossing has prompted this study. Focus-ing on the comprehensive utility tunnel over-crossing of metro shield tunnels, a three-dimensional fi-nite element model is developed to investigate the deformation mechanisms of segmental rings and joints induced by the over-crossing construction. Firstly, the stress-displacement relationship for seg-mental joints is established to simulate the force and deformation process between segments, validated through full-scale tests on segmental ring bearing performance. Secondly, a 3D finite element model of the shield tunnel structure and stratum is constructed based on engineering examples. Finally, com-parison between field monitoring and numerical simulations allows for a comprehensive analysis of lon-gitudinal tunnel deformations, ring misalignments, and joint shear forces. The results indicate that the primary utility tunnel crossing induces predominant tunnel heave, with the secondary crossing contrib-uting only 9％ to the maximum heave. Notably, the segmental rings exhibit vertical ovalization conver-gence within the main crossing area, with the tunnel crown experiencing the greatest heave displace-ment, measuring 1.15 times that of the tunnel waist and 1.35 times that of the tunnel invert. A stepped tunnel heave curve is observed longitudinally, primarily driven by circumferential joint misalignments induced by shear forces. The tunnel crown exhibits the largest misalignment, at 1.1 and 2 times greater than the tunnel waist and invert, respectively. The shear force around circumferential joints within the crossing area are unevenly distributed, with the tunnel crown and waist experiencing signifi-cant shear forces, while the tunnel invert faces minimal shear. Maximum shear forces around circum-ferential joints are located at the crossing edges, approximately 2.6 to 2.8 times higher than those at the center of the crossing range. These research findings offer valuable insights to support protection and monitoring strategies for shield tunnels during over-crossing tunneling operations.
万方数据
维普
