西安地裂缝界面处地震波传播规律
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摘要
地裂缝是黄土地区的一种典型地质灾害,地震波在地裂缝场地中的传播规律是工程界比较关心的一类问题。为了研究地震波在地裂缝处的传播规律,引用西安地区地裂缝界面的等效刚度系数和裂缝面的接触面连续条件,基于运动方程的基本解答,在考虑转换波产生的前提下得出了求解西安地裂缝处地震波透反射系数的频域方程组。对入射角、入射波频率和地裂缝介质等效力学参数的变化对地震波传播规律的影响进行了分析。结果表明,地裂缝对地震波的传播起到了一定的高频滤波作用,当入射波频率较低时波动的传播主要以透射波为主;等效法向刚度只影响P波的传播,等效切向刚度对P波和SV波都有影响;相对于法向刚度,切向刚度的变化对的透反射系数的影响更为明显。
Ground fissure is a typical geologic hazard in loess field and the propagation law of seismic wave in ground fissure field is widely concerned in engineering world. To analyze the propagation law of seismic wave across ground fissure, the equivalent rigid coefficients of ground fissure in Xi'an field and discontinuous condition of fissure interface are selected. Considering the converted waves, frequency domain equations used to solve the transmission and reflection coefficients are obtained based on the fundamental solutions of the equation of motion. The influence of the incident angle, frequency of incident wave and medium parameters of ground fissure on the propagation law of seismic wave is analyzed. A brief conclusion from the results is obtained that ground fissure possesses the high-frequency filtering properties with the propagation of seismic wave. In low frequency condition, the transmission coefficient is more larger than others. Equivalent normal rigidity only influences the propagation of P-wave, but equivalent shear rigidity influences P-and SV-wave. Relative to equivalent normal rigidity, the influence of the changes of equivalent shear rigidity on transmission and reflection coefficients is more obvious.
Ground fissure is a typical geologic hazard in loess field and the propagation law of seismic wave in ground fissure field is widely concerned in engineering world. To analyze the propagation law of seismic wave across ground fissure, the equivalent rigid coefficients of ground fissure in Xi'an field and discontinuous condition of fissure interface are selected. Considering the converted waves, frequency domain equations used to solve the transmission and reflection coefficients are obtained based on the fundamental solutions of the equation of motion. The influence of the incident angle, frequency of incident wave and medium parameters of ground fissure on the propagation law of seismic wave is analyzed. A brief conclusion from the results is obtained that ground fissure possesses the high-frequency filtering properties with the propagation of seismic wave. In low frequency condition, the transmission coefficient is more larger than others. Equivalent normal rigidity only influences the propagation of P-wave, but equivalent shear rigidity influences P-and SV-wave. Relative to equivalent normal rigidity, the influence of the changes of equivalent shear rigidity on transmission and reflection coefficients is more obvious.
引文
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[3]LI J C,WU W,LI H B,et al.A thin-layer interface model for wave propagation through filled rock joints[J].Journal of Applied Geophysics,2013,19:31-38.
[4]刘立波,李建春,李海波,等.应力波斜入射黏弹性节理的传播规律[J].岩石力学与工程学报,2012,32(增刊2):3593-3598.LIU Li-bo,LI Jian-chun,LI Hai-bo,et al.Propagation law of oblique incidence of stress wave across a viscoelastic joint[J].Chinese Journal of Rock Mechanics and Engineering,2012,32(Supp.2):3593-3598.
[5]SCHOENBERG M.Elastic wave behavior across linear slip interfaces[J].The Journal of the Acoustical Society of America,1980,68(5):1516-1521.
[6]RESENDE R,LAMAS L N,LEMOS J V,et al.Micromechanical modelling of stress waves in rock and rock fractures[J].Rock Mechanics and Rock Engineering,2010,43(6):741-761.
[7]LI J C,MA G W.Analysis of blast wave interaction with a rock joint[J].Rock Mechanics and Rock Engineering,2010,48:777-787.
[8]LI J C,MA G W,HUANG X.Analysis of wave propagation through a filled rock joint[J].Rock Mechanics and Rock Engineering,2010,43:789-798.
[9]LI J C,LI H B,JIAO Y Y,et al.Analysis for oblique wave propagetipn across filled joints based on thin-layer interface model[J].Journal of Applied Geophysics,2014,102:39-46.
[10]LI J C,LIU T T,LI H B,et al.Shear wave propagation across filled joints with the effect of interfacial shear strength[J].Rock Mechanics and Rock Engineering,2015,48:1547-1557.
[11]HUANG X L,QI S W,WILLIANS A,et al.Mumerical simulation of stress wave propagation through filled joins by particle model[J].International Journal of Solids and Structures,2015,69(70):23-33.
[12]胡宗正,高生,肖建华.断层面地震波反射的理论解[J].中国煤田地质,2004,16(3):44-47.HU Zong-zheng,GAO Sheng,XIAO Jian-hua.Theoretical seismic reflection induced by faults[J].Coal Geology of China,2004,16(3):44-47.
[13]LI J C,MA G W,ZHAO J.Analysis of stochastic seismic wave interaction with a slippery rock fault[J].Rock Mechanics and Rock Engineering,2011,44:85-92.
[14]宋彦辉,李忠生.长安地裂缝带黄土的微观结构特征研究[J].安全与环境工程,2012,19(6):17-21.SONG Yan-hui,LI Zhong-sheng.Research on the micro-texture characteristics of loess located in the ground fissure zone of Chang’an area[J].Safety and Environmental Engineering,2012,19(6):17-21.
[15]苑韦虹.地裂缝计算模型及参数研究[D].西安:长安大学建筑工程学院,2014.YUAN Wei-hong.Study on calculating model and parameters of ground fissure[D].Xi’an:School of Civil Engineering of Chang’an University 2014.