中文摘要：

在8级汶川地震和7级芦山地震这两次强震中,崩塌类斜坡灾害都占了次生灾害的绝大部分。崩塌灾害极具破坏性,主要是由于崩落滚石具有极强的冲击力造成的。根据2009年＂7.25＂彻底关大桥垮塌事故,结合三维有限元方法,采用HJC损伤机制建立的数值模型展开滚石冲击对大桥桥墩的动力分析。通过滚石对桥墩冲击过程的有限元模拟,从应力损伤、墩柱位移和冲击力特征三个方面研究了滚石冲击对桥墩破坏的影响,得到了桥墩应力场和位移场的变化特征。研究表明滚石冲击力具有明显的非线性特征,并对通过数值模拟和规范计算得到的冲击力进行对比分析,规范计算得到的冲击力偏小。因此对于被动拦挡结构的设计,相关指标应以最大冲击力为依据。

英文摘要：

Collapse disasters have accounted for the majority of secondary disasters in the Wenchuan earthquake （M_S=8.0） and Lushan earthquake （M_S=7.0）. Devastating collapse disasters mainly are caused by the strong impact of rolling stones. Based on the Chediguan Bridge accident which occurred on July 25 2009, and combining with the 3D finite element method, a numerical model proposed by HJC injury mechanism is used for the dynamic analysis to bridge piers due to rock falling impact. Through the finite element simulation of rock falling process, from the three aspects cf stress injury, pier displacement and impact force characteristics to research the influence on piers daraaged by rock falling, variation features of pier stress and displacement are obtained. The research shows that the rock fall impact force has obvious nonlinear characteristics, and after comparative analysis 1：o the impact force obtained by numerical simulation and calculated results by specifications, the impact force calculated by specifications is smaller. So the relative indicators of passive resistance structural design should be based on the maximum impact force.