爆破震动作用下斜坡体的地震动分布及其动应力响应特征
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摘要
利用爆破震动作为震源,观测、分析兰州市皋兰县城附近一黄土沟谷斜坡体的地震动分布情况及其动应力响应特征,为斜坡地震地质灾害的易发性研究提供科学依据。试验分析表明:(1)斜坡体上的地震动最大幅值变化明显受地形条件控制,斜坡中上部强震观测点QZH14所处部位地势内凹,对地震波有汇聚作用,其水平分量PGA明显大于周边其他测点。(2)爆破地震动作用下河谷底部反应谱以单峰型为主,斜坡体上为双峰型,反映河谷底部与斜坡体不同结构地质体的地震动特征。(3)爆破试验场地同一位置处的地震动与其动应力响应具有很好的对应关系,地震动幅值大的部位土体的动力响应也较大;斜坡体不同埋深部位的土体动力响应并不一定表现出一致增大或减小的规律,受地形和岩土结构等影响可能存在显著差异。研究认为地震动幅值、频率特征、地震波的入射角度等因素通过影响斜坡体的地震动参数变化,进而影响地震地质灾害的发育程度。
According to the seismic records,ground motion parameters are significant difference on various parts of alpine and gorge region,where earthquake damage investigation shows the damage is more serious than wide flat terrain and secondary disaster occurs frequently. In order to reveal the mechanisms of action,characteristics of blasting ground motion and the corresponding dynamic stress response,the blasting ground motion test for a loess valley slope located in Gaolan County,Lanzhou is carried. The testing analysis shows that:(1) Ground motion on the slope is obviously controlled by topography,especially in the cove(QZH14) on upper part of slope,where the PGA is higher than nearby observation points due to the wave superposition.(2) The response spectrum of blasting shows two attributes of ground motion on the slope and the foot of valley-bimodal pattern the former and unimodal pattern the latter. On the slope,long period component attenuates slowly with the hypocentral distance increasing.(3) There is a apparent correspondence between ground motion and its dynamic stress response,higher amplitude of ground motion,larger dynamic stress response. Due to the topographic effect and the geotechnical structure,inner stress response of the slope emerges significant variation in different depths rather than increasing or reducing trend with the distance of macro-epicenter increase. It suggests that the development degree of earthquake induced geological disasters are affected by the parameter variation of strong ground motion on the slope,which is usually determined by various factors,amplitude,frequency characteristics and incidence angle of seismic wave etc.
According to the seismic records,ground motion parameters are significant difference on various parts of alpine and gorge region,where earthquake damage investigation shows the damage is more serious than wide flat terrain and secondary disaster occurs frequently. In order to reveal the mechanisms of action,characteristics of blasting ground motion and the corresponding dynamic stress response,the blasting ground motion test for a loess valley slope located in Gaolan County,Lanzhou is carried. The testing analysis shows that:(1) Ground motion on the slope is obviously controlled by topography,especially in the cove(QZH14) on upper part of slope,where the PGA is higher than nearby observation points due to the wave superposition.(2) The response spectrum of blasting shows two attributes of ground motion on the slope and the foot of valley-bimodal pattern the former and unimodal pattern the latter. On the slope,long period component attenuates slowly with the hypocentral distance increasing.(3) There is a apparent correspondence between ground motion and its dynamic stress response,higher amplitude of ground motion,larger dynamic stress response. Due to the topographic effect and the geotechnical structure,inner stress response of the slope emerges significant variation in different depths rather than increasing or reducing trend with the distance of macro-epicenter increase. It suggests that the development degree of earthquake induced geological disasters are affected by the parameter variation of strong ground motion on the slope,which is usually determined by various factors,amplitude,frequency characteristics and incidence angle of seismic wave etc.
引文
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[9]王秀英,聂高众,王登伟.汶川地震诱发滑坡与地震动峰值加速度对应关系研究[J].岩石力学与工程学报,2010,29(1):82–89.(WANG Xiuying,NIE Gaozhong,WANG Dengwei.Research on relationship between landslide and peak ground accelerations induced by Wenchuan earthquake[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(1):82–89.(in Chinese))
[10]LAWRENCE L D,LEWIS R W.Observed effects of topography on ground motion[J].Bulletin of the Seismological Society of America,1973,63(1):283–298.
[11]LANGSTON C A,BODIN P,POWELL C,et al.Explosion source strong ground motions in the Mississippi embayment[J].Bulletin of the Seismological Society of America,2006,96(3):1 038–1 054.
[12]JEMBERIE A L.Study of sediment nonlinearity using explosion data in the Mississippi embayment[J].Pure and Applied Geophysics,2008,165(9/10):1 835–1 860.
[13]王兰民,孙军杰,徐舜华,等.爆破模拟地震动条件下黄土场地震陷研究[J].岩石力学与工程学报,2008,27(5):913–921.(WANG Lanmin,SUN Junjie,XU Shunhua,et al.Characteristics of seismic subsidence of loess site induced by blasting ground motion[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(5):913–921.(in Chinese))
[14]孙军杰,秋仁东,徐舜华,等.微差爆破引发黄土场地强地面运动特征研究[J].岩石力学与工程学报,2011,30(增2):3 728–3 738.(SUN Junjie,QIU Rendong,XU Shunhua,et al.Characteristics of ground motion induced by a short delay blasting in loess field[J].Chinese Journal of Rock Mechanics and Engineering,2011,30(Supp.2):3 728–3 738.(in Chinese))
[15]陈士海.爆破地震动研究现状[J].爆破,2003,20(增):13–18.(CHEN Shihai.Present situation of research on blasting vibration[J].Blasting,2003,20(Supp.):13–18.(in Chinese))
[16]孙新建.爆破地震动速度时程的反应谱分析[J].太原理工大学学报,2008,39(增):309–312.(SUN Xinjian.Response spectrum analysis of blasting vibration velocity temporal curve[J].Journal of Taiyuan University of Technology,2008,39(Supp.):309–312.(in Chinese))
[17]李洪涛,卢文波,舒大强,等.爆破地震波的能量衰减规律研究[J].岩石力学与工程学报,2010,29(增1):3 364–3 369.(LI Hongtao,LU Wenbo,SHU Daqiang,et al.Study of energy attenuation law of blast-induced seismic wave[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(Supp.1):3 364–3 369.(in Chinese))
[2]HARP E L,JIBSON R W.Landslides triggered by the 1994Northridge,California,earthquake[J].Bulletin of the Seismological Society of America,1996,86(B1):319–332.
[3]JIBSON R W,PRENTICE C S,BORISSOFF B A,et al.Some observations of landslides triggered by 29 April,1991 Racha earthquake,Republic of Georgia[J].Bulletin of the Seismological Society of America,1994,84(4):963–973.
[4]王伟.地震动的山体地形效应[博士学位论文][D].哈尔滨:中国地震局工程力学研究所,2011.(WANG Wei.Study of hill topography effect on ground motion[Ph.D.Thesis][D].Harbin:Institute of Engineering Mechanics,China Earthquake Administration,2011.(in Chinese))
[5]卢育霞,刘琨,石玉成,等.甘肃文县上城台地的地震记录分析[J].西北地震学报,2011,33(增):393–397.(LU Yuxia,LIU Kun,SHI Yucheng,et al.Analysis on seismic records observed on Shangcheng platform in Wenxian,Gansu province[J].Northwestern Seismological Journal,2011,33(Supp.):393–397.(in Chinese))
[6]周国良,李小军,侯春林,等.SV波入射下河谷地形地震动分布特征分析[J].岩土力学,2012,33(4):1 161–1 166.(ZHOU Guoliang,LI Xiaojun,HOU Chunlin,et al.Characteristic analysis of ground motions of canyon topography under incident SV seismic waves[J].Rock and Soil Mechanics,2012,33(4):1 161–1 166.(in Chinese))
[7]王运生,罗永红,吉峰,等.汶川大地震山地灾害发育的控制因素分析[J].工程地质学报,2008,16(6):759–763.(WANG Yunsheng,LUO Yonghong,JI Feng,et al.Analysis of the controlling factors on geo-hazards in mountainous epicenter zones of the Wenchuan earthquake[J].Journal of Engineering geology,2008,16(6):759–763.(in Chinese))
[8]韩金良,吴树仁,何淑军,等.5·12汶川8级地震次生地质灾害的基本特征及其形成机制浅析[J].地学前缘,2009,16(3):306–326.(HAN Jinliang,WU Shuren,HE Shujun,et a1.Basal characteristics and formation mechanisms of geological hazards triggered by the May12,2008 Wenchuan earthquake with a moment magnitude of 8.0[J].Earth Science Frontiers,2009,16(3):306–326.(in Chinese))
[9]王秀英,聂高众,王登伟.汶川地震诱发滑坡与地震动峰值加速度对应关系研究[J].岩石力学与工程学报,2010,29(1):82–89.(WANG Xiuying,NIE Gaozhong,WANG Dengwei.Research on relationship between landslide and peak ground accelerations induced by Wenchuan earthquake[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(1):82–89.(in Chinese))
[10]LAWRENCE L D,LEWIS R W.Observed effects of topography on ground motion[J].Bulletin of the Seismological Society of America,1973,63(1):283–298.
[11]LANGSTON C A,BODIN P,POWELL C,et al.Explosion source strong ground motions in the Mississippi embayment[J].Bulletin of the Seismological Society of America,2006,96(3):1 038–1 054.
[12]JEMBERIE A L.Study of sediment nonlinearity using explosion data in the Mississippi embayment[J].Pure and Applied Geophysics,2008,165(9/10):1 835–1 860.
[13]王兰民,孙军杰,徐舜华,等.爆破模拟地震动条件下黄土场地震陷研究[J].岩石力学与工程学报,2008,27(5):913–921.(WANG Lanmin,SUN Junjie,XU Shunhua,et al.Characteristics of seismic subsidence of loess site induced by blasting ground motion[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(5):913–921.(in Chinese))
[14]孙军杰,秋仁东,徐舜华,等.微差爆破引发黄土场地强地面运动特征研究[J].岩石力学与工程学报,2011,30(增2):3 728–3 738.(SUN Junjie,QIU Rendong,XU Shunhua,et al.Characteristics of ground motion induced by a short delay blasting in loess field[J].Chinese Journal of Rock Mechanics and Engineering,2011,30(Supp.2):3 728–3 738.(in Chinese))
[15]陈士海.爆破地震动研究现状[J].爆破,2003,20(增):13–18.(CHEN Shihai.Present situation of research on blasting vibration[J].Blasting,2003,20(Supp.):13–18.(in Chinese))
[16]孙新建.爆破地震动速度时程的反应谱分析[J].太原理工大学学报,2008,39(增):309–312.(SUN Xinjian.Response spectrum analysis of blasting vibration velocity temporal curve[J].Journal of Taiyuan University of Technology,2008,39(Supp.):309–312.(in Chinese))
[17]李洪涛,卢文波,舒大强,等.爆破地震波的能量衰减规律研究[J].岩石力学与工程学报,2010,29(增1):3 364–3 369.(LI Hongtao,LU Wenbo,SHU Daqiang,et al.Study of energy attenuation law of blast-induced seismic wave[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(Supp.1):3 364–3 369.(in Chinese))
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