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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。
In the two strong earthquakes such as Wenchuan Ms8 earthquake and Ms7 Lushan earthquake, the collapse-type slope disasters accounted for the majority of the secondary disasters. Collapse disaster is very destructive, mainly due to the strong impact of falling rock. According to 2009 “7.25 ” thorough investigation of the collapse of the bridge, combined with the three-dimensional finite element method, the numerical model established by the damage mechanism of HJC was used to develop the dynamic analysis of the roller pier impact on the bridge pier. Through the finite element simulation of the impact process of the bridge pier by rolling stones, the impact of the rolling stone impact on the pier failure is studied from the aspects of stress damage, pier displacement and impact characteristics, and the changing characteristics of the stress field and the displacement field are obtained. The research shows that the impact force of rolling stones has obvious nonlinear characteristics, and comparative analysis of the impact force obtained through numerical simulation and standard calculation shows that the impact force calculated by the standard is small. Therefore, for passive block structure design, the relevant indicators should be based on the maximum impact.