层状岩体斜坡强震动力响应的振动台试验
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摘要
通过大型振动台试验,研究反倾和顺层两类结构岩体边坡在强震条件下的地震动力响应。结果表明:强震条件下,斜坡对水平地震动力的响应要远超过垂直地震动力,前者所导致的加速度响应峰值(PGA)放大系数是后者的2～3倍。在水平地震动力作用下,斜坡的地震动响应具有显著的高程效应和结构效应。对于硬岩顺层斜坡在1/2倍坡高以上坡面和坡内均出现显著的PGA放大效应;而硬岩反倾斜坡的放大效应则主要表现在坡体内部1/2倍坡高以上和坡体表部2/3倍坡高以上,且放大幅度要高于顺层斜坡。软岩斜坡在水平地震力作用下的动力响应总体上较硬岩斜坡弱,顺层斜坡表现为1/2倍坡高后,PGA放大系数的持续增大,而反倾斜坡主要表现为坡表中下部(1/4倍坡高处)和3/4倍坡高以上PGA的突然增大。模型在强震条件下的破裂观测结果表明:硬岩顺层斜坡(HD)在变形破坏通常表现为顺层滑移–下部隆起溃屈型失稳;硬岩反倾斜坡(HAD)为后缘垂直拉裂–中下部平缓剪出型失稳(L型滑面);软岩顺层斜坡(SD)为顺层滑移–底部挤出–分层滑移型失稳;软岩反倾斜坡(SAD)为斜坡顶部拉裂–下部剪出型失稳。试验结果与现场观察现象能较好吻合,从而深入揭示强震条件下层状结构斜坡的地震动力响应和失稳破坏机制。
By means of large-scale shaking table test,the dynamic responses of stratified hard rock and soft rock slopes with anti-dipping strata and dipping strata to strong earthquakes are studied.The results are listed as follows:under the shaking of strong earthquakes,the response of slopes to horizontal seismic force exceeded that to vertical seismic force,for peak ground acceleration(PGA) amplification coefficient resulting from the former was 2 to 3 times that of the latter.Under the horizontal seismic force,the seismic dynamic response of slopes should have significant elevation effect and structure effect.For hard rock bedding slope,significant PGA amplification coefficient was found on the surface and inside above the 1/2 slope height;while the amplification coefficient of hard rock anti-dipping slopes mainly appeared inside the upper 1/2 slope height and on the surface above the 2/3 slope height,and the amplification extent was higher than that of bedding slope.In general,the dynamic response of soft rock slope to horizontal earthquake force was weaker than that of hard rock slope.For bedding slope,PGA amplification coefficient constantly became larger above the 1/2 slope height.For anti-dipping slope,PGA suddenly became larger below the 1/4 slope height and above the 3/4 slope height.The fracture observation of testing model under strong earthquake shaking implied the following results:the deformation and failure of hard rock bedding slopes showed plane sliding in the trailing edge-extrusion and buckling at the bottom of the slopes.Hard rock anti-dipping slope displayed vertical tensile splitting in the trailing gently shearing in the lower-middle parts(L sliding surface).Soft rock bedding slope was plane sliding in the trailing edge-extrusion and layered-slipping at the bottom.Soft rock anti-dipping slope showed tensile splitting at the top-tensile splitting at the bottom.The testing results coincided with the observation of field investigation;so that the seismic dynamic response and instability failure mechanism of stratified slope under strong earthquake shaking were revealed.
By means of large-scale shaking table test,the dynamic responses of stratified hard rock and soft rock slopes with anti-dipping strata and dipping strata to strong earthquakes are studied.The results are listed as follows:under the shaking of strong earthquakes,the response of slopes to horizontal seismic force exceeded that to vertical seismic force,for peak ground acceleration(PGA) amplification coefficient resulting from the former was 2 to 3 times that of the latter.Under the horizontal seismic force,the seismic dynamic response of slopes should have significant elevation effect and structure effect.For hard rock bedding slope,significant PGA amplification coefficient was found on the surface and inside above the 1/2 slope height;while the amplification coefficient of hard rock anti-dipping slopes mainly appeared inside the upper 1/2 slope height and on the surface above the 2/3 slope height,and the amplification extent was higher than that of bedding slope.In general,the dynamic response of soft rock slope to horizontal earthquake force was weaker than that of hard rock slope.For bedding slope,PGA amplification coefficient constantly became larger above the 1/2 slope height.For anti-dipping slope,PGA suddenly became larger below the 1/4 slope height and above the 3/4 slope height.The fracture observation of testing model under strong earthquake shaking implied the following results:the deformation and failure of hard rock bedding slopes showed plane sliding in the trailing edge-extrusion and buckling at the bottom of the slopes.Hard rock anti-dipping slope displayed vertical tensile splitting in the trailing gently shearing in the lower-middle parts(L sliding surface).Soft rock bedding slope was plane sliding in the trailing edge-extrusion and layered-slipping at the bottom.Soft rock anti-dipping slope showed tensile splitting at the top-tensile splitting at the bottom.The testing results coincided with the observation of field investigation;so that the seismic dynamic response and instability failure mechanism of stratified slope under strong earthquake shaking were revealed.
引文
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[13]祁生文,伍法权.边坡动力响应规律研究[J].中国科学(E辑):技术科学,2003,33(增):28–40.(QI Shengwen,WU Faquan.Study ondynamic responses of slope[J].Science in China(Series E):Technological Science,2003,33(Supp.):28–40.(in Chinese))
[14]GRIFFITHS D W,BOLLINGER G A.The effect of appalachianmountain topography on seismic waves[J].Bulletin of the SeismologicalSociety of America,1979,69(4):1 081–1 105.
[15]张倬元,王石天,王兰生,等.工程地质分析原理[M].北京:地质出版社,1993:212–224.(ZHANG Zhuoyuan,WANG Shitian,WANG Lansheng,et al.Principles of engineering geology[M].Beijing:Geology Press,1993:212–224.(in Chinese))
[2]李果,黄润秋,巨能攀,等.龙门山地区震后次生灾害发育分布规律研究[J].人民长江,2011,42(4):23–28.(LI Guo,HUANGRunqiu,JU Nengpan,et al.Study of distribution and developmentlaws of secondary disaster in Longmenshan area after earthquake[J].Yangtze River,2011,42(4):23–28.(in Chinese))
[3]黄润秋,唐川,李勇,等.汶川地震地质灾害研究[M].北京:科学出版社,2009:260–270.(HUANG Runqiu,TANG Chuan,LI Yong,et al.Geohazard assessment of the Wenchuan earthquake[M].Beijing:Science Press,2009:260–270.(in Chinese))
[4]许强,裴向军,黄润秋.汶川地震大型滑坡研究[M].北京:科学出版社,2009:19–52.(XU Qiang,PEI Xiangjun,HUANG Runqiu.Large-scale landslides induced by the Wenchuan earthquake[M].Beijing:Science Press,2009:19–52.(in Chinese))
[5]赵建军,巨能攀,李果,等.汶川地震诱发罐滩滑坡形成机制初步分析[J].地质灾害与环境保护,2010,21(2):92–96.(ZHAOJianjun,JU Nengpan,LI Guo,et al.Failure mechanism analysis ofGuantan landslide induced by Wenchuan earthquake[J].Journal ofGeological Hazards and Environment Preservation,2010,21(2):92–96.(in Chinese))
[6]许强,刘汉香,邹威,等.斜坡加速度动力响应特性的大型振动台试验研究[J].岩石力学与工程学报,2010,29(12):2420–2428.(XU Qiang,LIU Hanxiang,ZOU Wei,et al.Large-scale shaking tabletest study of acceleration dynamic responses characteristics ofslopes[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(12):2 420–2 428.(in Chinese))
[7]刘汉香,许强,徐鸿彪,等.斜坡动力变形破坏特征的振动台模型试验研究[J].岩土力学,2011,32(增2):334–339.(LIUHanxiang,XU Qiang,XU Hongbiao,et al.Shaking table model teston slope dynamic deformation and failure[J].Rock and SoilMechanics,2011,32(Supp.2):334–339.(in Chinese))
[8]董金玉,杨国香,伍法权,等.地震作用下顺层岩质边坡动力响应和破坏模式大型振动台试验研究[J].岩土力学,2011,32(10):2977–2 983.(DONG Jinyu,YANG Guoxiang,WU Faquan,et al.Thelarge-scale shaking table test study of dynamic response and failuremode of bedding rock slope under earthquake[J].Rock and SoilMechanics,2011,32(10):2 977–2 983.(in Chinese))
[9]袁文忠.相似理论与静力学模型试验[M].成都:西南交通大学出版社,1998:112–119.(YUAN Wenzhong.Simulation theory andstatic model test[M].Chengdu:Southwest Jiaotong University Press,1998:112–119.(in Chinese))
[10]张敏政.地震模拟实验中相似律应用的若干问题[J].地震工程与工程振动,1997,17(2):52–58.(ZHANG Minzheng.Study ofsimilitude laws for shaking table tests[J].Earthquake Engineering andEngineering Vibration,1997,17(2):52–58.(in Chinese))
[11]林皋,朱彤,林蓓.结构动力模型试验的相似技巧[J].大连理工大学学报,2000,40(1):1–8.(LIN Gao,ZHU Tong,LIN Bei.Similarity technique for dynamic structural model test[J].Journal ofDalian University of Technology,2000,40(1):1–8.(in Chinese))
[12]罗先启,葛修润.滑坡模型试验理论及其应用[M].北京:中国水利水电出版社,2008:44–49.(LUO Xianqi,GE Runxiu.Theory andapplication of model test on landslide[M].Beijing:China Water PowerPress,2008:44–49.(in Chinese))
[13]祁生文,伍法权.边坡动力响应规律研究[J].中国科学(E辑):技术科学,2003,33(增):28–40.(QI Shengwen,WU Faquan.Study ondynamic responses of slope[J].Science in China(Series E):Technological Science,2003,33(Supp.):28–40.(in Chinese))
[14]GRIFFITHS D W,BOLLINGER G A.The effect of appalachianmountain topography on seismic waves[J].Bulletin of the SeismologicalSociety of America,1979,69(4):1 081–1 105.
[15]张倬元,王石天,王兰生,等.工程地质分析原理[M].北京:地质出版社,1993:212–224.(ZHANG Zhuoyuan,WANG Shitian,WANG Lansheng,et al.Principles of engineering geology[M].Beijing:Geology Press,1993:212–224.(in Chinese))
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