岩性及岩体结构对斜坡地震加速度响应的影响  

Influence of lithology and rock structure on slope seismic acceleration responses

作　　者：刘汉香[1] 许强[1] 侯红娟[1] 

机构地区：[1]成都理工大学地质灾害防治与地质环境保护国家重点实验室,成都610059

出　　处：《岩土力学》2013年第9期2482-2488,共7页Rock and Soil Mechanics

基　　金：国家重点基础研究发展计划课题(No.2008CB425801);教育部创新团队发展计划(No.IRT0812);地质灾害防治与地质环境保护国家重点实验室自主研究课题"汶川地震大型滑坡研究"

摘　　要：斜坡岩体的岩性及岩体结构是斜坡在地震作用下产生变形破坏的主要控制因素。基于振动台模型试验,对4个斜坡模型探讨了这2个因素对斜坡地震动力响应的影响。岩性包括强度相对较高的硬岩和强度相对较低的软岩,对这两种岩性的斜坡又分别考虑了不含结构面的均质斜坡和含水平层状结构面的斜坡。基于传感器采集到的大量数据,以主频相近的天然地震波和10 Hz正弦波加载为分析工况,获得了以下几点认识:(1)4个模型斜坡坡面和坡内的水平向加速度均具有高程放大效应,尤其是软岩斜坡坡顶放大效应最显著;(2)软岩斜坡对水平向加速度的高程放大效应强于硬岩斜坡,尤其是在均质斜坡中表现最显著,均质软岩斜坡的高程放大效应呈现出明显的非线性特征;(3)当加载方向与水平层面平行时,含水平层状结构面的斜坡比均质斜坡产生了更强的高程放大效应,且在软岩斜坡中体现最显著;(4)岩性差异对斜坡水平向加速度高程效应的影响比结构差异的影响更为显著。研究结果为岩质斜坡的抗震设计提供了一定参考。Lithology and rock structure of a rock slope are two of the most important controlling factors on its deformation and failure process during earthquake. Four shaking table models of slopes are designed to explore the effects of the above two factors on slope seismic responses. Referring to lithology, hard rock with high strength and soft rock with low strength are modeled, at the same time, an isotropic slope and a horizontally layered slope are selected for each kind of lithology. Based on a large number of sensor recordings, results are analyzed under excitations of both the real waves and sine waves which have the similar predominant frequency. The main conclusions are drawn as follows： （1） The horizontal accelerations on the slope surface and inside the slope demonstrate topographic amplification effect for all the 4 model slopes; and the maximum amplification factor occuring at the crest of the soft rock slope model; （2） The topographic effects in soft rock slopes are stronger than those in hard rock slopes, which is more obvious in the two isotropic rock slopes, and the topographic effect in the isotropic and soft rock slope depict nonlinear change laws. （3） When the shaking direction accords with the horizontal structure surface just as in the present study, the layered slopes demonstrate stronger topographic amplification effect for horizontal accelerations, especially in soft rock slopes; （4） Lithology plays a more important role in topographic effect than discontinuity in a rock slope during earthquake. The results provide a reference for the seismic design of rock slopes.

关 键 词：斜坡 岩性 岩体结构 天然波 正弦波 加速度响应 

分 类 号：TU452[建筑科学—岩土工程]