Abstract:To study the seismic response characteristics of large-section rectangular shield tunnel, a dynamic time-history finite element analysis model for seismic computations of the cross section of large-section rectangular shield tunnel is established by taking the Shanghai Hongqiao Underground Connection Channel Project as a case study. The numerical model accounts for the dynamic characteristics of soft soil in Shanghai and the joints of lining segments. The dynamic interaction between the site soil and the rectangular tunnel structure is reasonably simulated. By establishing a homogeneous rigidity segment model, the influence of segment joints on the dynamic response of the rectangular tunnel is compared and analyzed, and the influencing rule of segment joint rotary rigidity change on the interlayer displacements and internal structural forces are further discussed. The results show that the dynamic response of the homogeneous rigidity model is greater than that of the segment joint model. Compared with the segment joint model, the homogeneous rigidity model is hard to show up the segment dislocation and the internal force mutation at the joint places. Furthermore, the peak bending moment and axial force value are obviously increased, in which the peak of bending moment is increased up to 2.29 times. It is suggested to adopt the segment joint model in the rectangular seismic design. The influence of the rotational rigidity of segment joint on the dynamic response of rectangular tunnel is obvious. With the joint rigidity decreases, the structural interlayer displacement gradually increases, but the peak bending moment and shearing force of the segments significantly reduce, which can provide a scientific basis for the seismic design of large-section rectangular shield tunnels.
