Multi-Scale Method and Seismic Response Analysis of Immersed Tunnel

Abstract:

In view of the shortcomings of the current simplified seismic analysis model of immersed tunnel with multi-mass-spring， such as the inability to reasonably simulate the detailed structure and mechanical characteristics of tube joints， a multi-scale analysis model was proposed， which simultaneously characterizes the macroscopic response and the microscopic joint structure of the immersed tunnel. The macroscopic multi-mass-spring-beam model was used to describe the macroscopic seismic response characteristics and the dynamic interaction between structure and stratum. The microscopic refinement model was used to capture the dynamic laws of the relative deformation of joints and the stress of shear keys. Taking an immersed tunnel in Guangzhou as an application example， the corresponding multi-scale model was established. Considering the combination of calculation conditions such as ground motion input direction and environmental temperature change， the seismic response characteristics of the immersed tunnel structure， the joint deformation， the shear key stress， and the influence law of key factors were studied. The results show that with the increase of the angle between the input direction of ground motion and the axial direction of the tunnel， the shear force and bending moment of the structure increase significatly， while the axial force and joint deformation decrease. The peak axial force decreases by more than 85% when the input direction is 90°， while the maximum joint tension is only 17% of that when the input direction is 0°. The change of temperature has a significant influence on the axial force and joint deformation. The maximum opening of joint increases by about 30% due to the temperature drop， and the tensile force of the tunnel is close to 60% of the peak axial force.

Key words:tunnel engineering;immersed tunnel;multi-scale method;seismic response;temperature change