大型地下洞室群关键块体地震响应分析

基于块体理论，针对地下厂房围岩中的关键块体，采用Newmark法进行了地震响应特征和稳定性评价方法的研究，研究表明，三向地震荷载组合作用下，在块体上引起的数值较大、作用时间很短的惯性力是关键块体产生永久位移的根本原因。块体在不同烈度地震荷载作用下其响应特征不只发生量的变化，还有运动规律、模式方面的变化。研究还发现，关键块体地震响应特征与其几何特征存在一定的相关性，并由此建立了大型地下洞室群围岩地震稳定分析的多因素、多指标评判方法。最后考虑结构面的退化效应，研究了块体地震响应特征关于结构面强度参数的敏感性，获得了一些有益的结论。

Study of seismic response of key block in large underground opening group

Based on the block theory and Newmark sliding block method, seismic response and stability of key block in large underground opening group are studied. It is found that inertia force of the key block which acting with short time and large force leads to generation of permanent displacement under three-direction seismic loads, and seismic loads with different intensities cause the key block not only quantitative change of seismic response but also motion regularity and patterns. The result also shows that seismic response characteristics is related to the depth and volume of key blocks through statistic analysis; and seismic stability evaluation method considering multiple factor and indexes is established according to key blocks in large underground opening group. Finally, seismic response of the key block is studied considering cyclic degradation of structure plane strength; and some beneficial conclusions are drawn.