基于广义反应位移法的过江盾构隧道纵向地震反应分析

为了解决在强震作用下大型盾构隧道纵向地震反应分析困难的问题,以武汉市三阳路过江盾构隧道工程为依托,构建了该盾构隧道二维非线性自由场地数值模型及盾构隧道整体纵向精细化梁-弹簧模型,研究了不同强度、不同频谱特性的地震动作用下盾构隧道沿纵向管环间的张开量.结果表明:不同工况下,盾构隧道相邻管环间张开量沿纵向走势呈现相似性,同一地震动作用下,张开量随着地震动强度的增加而呈非线性增长;地震动频谱特性对隧道纵向地震反应影响很大,环间张开量呈现高频减小,低频放大现象;在砂层与基岩面交界处,隧道环间张开量出现异常突变现象,在Darfield波、PGA=0.4工况下局部位置超过了一般防水措施允许的张开量最大值.计算结果为盾构隧道结构的纵向抗震设计提供了一定参考依据.

Crossing-river Shield Tunnel Longitudinal Seismic Response Analysis Based on Generalized Displacement Method

A large number of China's large shield tunnel project is located in strong earthquake area so it is very necessary to study the seismic response of large shield tunnel under earthquake. As far as the crossing-river shield tunnel built in Sanyang road, Wuhan city was concerned, a two-dimensional numerical model of nonlinear tunnel free field of the shield and shield tunnel overall fine longitudinal beam spring model were built. Opening value between ring intersegments along the longitudinal was studied in the different intensity and different spectrum characteristics of earthquake motion. Results demonstrate that the shield tunnel adjacent opening value extreme along the longitudinal trend has similarity under different conditions, and opening value extreme increases nonlinear with the increase of intensity in the same earthquake motion. The seismic frequency spectrum has great influence on the longitudinal seismic response of the tunnel, and the opening value extreme exhibits high frequency reduction and low frequency amplification. In the sand layer and the bedrock surface at the junction,the opening value shows the phenomenon of abnormal mutation. In the Darfield wave,PGA=0.4 conditions, the local position exceeds the general waterproof measures to allow the opening limit. The calculation results provide a reference for the longitudinal seismic design of shield tunnel structure.