基于改进动力强度折减法的隧道地震破坏机理探讨

摘要

To explore the failure mechanism of tunnel structures in earthquakes, a static field was imposed to dy-namic calculation by shifting the boundary between static and dynamic, which was taken as an initial stress con-dition for the improvement of the dynamic strength reduction method, the feasibility of which was proven by a computing application. The improved dynamic strength reduction method is used to calculate and analyze the failure mechanism of deep and shallow buried tunnels under seismic action, and the results show that failure pro-cesses are different for tunnels with different depths. For the shallow-buried tunnel, failure begins at the two sides above the tunnel and gradually forms a fracture plane cutting through the ground; for the deep tunnel, the plastic strain first occurs at four stress-concentrated corners with a smaller plastic strain on the crown and floor, and then a continuous plastic strain zone is formed gradually from the two sides until failure finally occurs. In light of seismic action, this paper analyzes the factors affecting tunnel failure, studies the failure mechanism of tunnel structures of different surrounding rock grades, spans, structure types, and buried depths, and finally car-ries on a comparative analysis for each influence factor.%文章分析了影响隧道在地震作用下破坏的因素，研究了不同围岩级别、不同跨度、不同结构形式和不同埋深等条件下隧道结构在地震中的破坏机理，分别针对各个影响因素进行了对比分析；通过静动力转换边界将静力场施加到动力计算中作为初始应力条件，对动力强度折减法进行了改进，通过计算应用证明了其可行性；使用改进的动力强度折减法对深、浅埋隧道在地震作用下的破坏机理进行了计算分析。结果表明，不同埋深隧道在地震中的破坏过程不同，浅埋隧道是从隧道上方两侧开始破坏的，逐渐形成贯通到地面的破裂面；深埋隧道最先在4个边角的应力集中处出现塑性应变，顶部和底部的塑性应变较小，随后从两侧开始逐渐形成贯通的塑性应变区，直至破坏。