地下综合管廊土-结构接触面参数对地震动力响应的影响数值分析

为研究土-结构接触面参数对地下综合管廊地震动力响应特征的影响,建立动力有限元数值模型,模型边界采用激励侧固定边界、远离激励侧黏性边界、其余侧自由场边界的优化组合动力边界,土体本构采用HSS模型,接触面采用改进Goodman单元,动力荷载考虑三种情况(Rayleigh波的作用、底部激励了美国加利福尼亚Upland地震波以及前两者的共同作用),分别研究不同地震动输入、接触面折减系数的改变对综合管廊内力及加速度的影响。研究结果表明:在相同的折减系数条件下,与静力作用相比,动力作用下的结构内力明显增大,综合管廊设计时应考虑地震荷载作用下内力增大的情况;随着界面折减系数的增加,正弯矩极值减小,负弯矩极值增大,加速度峰值增大;在相同接触面折减系数条件下,底部地震波输入产生的结构内力极值显著高于仅有Rayleigh波输入的情况;考虑Rayleigh波和地震波共同作用条件下,引起的管廊结构内力极值与仅考虑底部地震波输入时的结构内力极值差异不大。研究成果可供地下综合管廊结构地震响应精细化数值模拟及抗震设计参考。

Numerical Analysis of the Influence of Soil-structure Interface Parameters on the Seismic Dynamic Response of Underground Utility Tunnels

To investigate the influence of soil-structure interface parameters on the seismic dynamic response of underground utility tunnels, in this study we built a dynamic finite element numerical model to probe the influence of changes in seismic input motion and interface reduction factors on the internal force and acceleration in utility tunnels. In the model, an optimized combination of boundary conditions was adopted wherein the excitation-applied side was a fixed boundary, the excitation-free side a viscous boundary, and the rest free-field boundaries. A small-strain stiffness model was employed as the constitutive soil model, a modified Goodman element was used to model the interface, and the dynamic load took into account three conditions:the effects of Rayleigh waves, the effects of bottom seismic waves (as those in Upland, California), and the combined effects of the two. The results showed that when the reduction factor remained unchanged, the structural internal force was greater under dynamic than under static force. Therefore, the situation wherein there is an increase in internal force under seismic loads should be considered in the design of utility tunnels. When the reduction factor increased, the extreme value of the sagging moment decreased, the extreme value of hogging moment increased, and the peak acceleration value increased. When the reduction factor remained the same, the extreme value of the structural internal force generated by bottom seismic waves was higher than that generated by Rayleigh waves. However, under the combined effect of Rayleigh and seismic waves, the extreme value of the structural internal force generated differed very slightly from that when only seismic waves were input. The research findings are expected to provide a reference for elaborate numerical simulations of the seismic response of underground utility tunnels and their seismic design.