沉管隧道多尺度方法与地震响应分析

Multi-Scale Method and Seismic Response Analysis of Immersed Tunnel

摘要:

针对目前沉管隧道多质点-弹簧抗震简化分析模型的不足，如无法合理模拟沉管接头的细部构造及力学特征，提出了一种同时表征沉管隧道宏观整体响应和细观接头构造的多尺度分析方法，其中宏观多质点-弹簧-梁耦合模型用于描述沉管隧道结构与地层的动力相互作用以及宏观整体地震响应特征，细观精细化模型用于捕捉沉管接头的张合量、剪力键受力等动态演化规律。以广州某沉管隧道为应用实例，建立了相应的地震响应多尺度分析模型，综合考虑地震动输入方向、运营期环境温度变化等工况组合，研究了沉管隧道管节受力、接头变形、剪力键受力等地震响应特性以及关键因素的影响规律。结果表明，地震动输入方向随着与隧道轴向夹角的增加，结构剪力及弯矩明显增大，而轴力及接头变形随之减小，90°输入时峰值轴力的降幅超过了85%，而接头最大张合量仅为0°输入时的17%；环境温度变化对沉管隧道轴向受力及接头变形影响显著，降温导致接头最大张开量增加了约30%，并使隧道出现了接近峰值轴力60%的拉力。

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.