【摘要】 利用三维有限元数值模拟方法,定量研究了介质不均匀性和断层倾角变化对同震位移场的影响。模拟结果显示:1)在均匀及纵向分层介质模型中,对于垂直走滑断层地震,水平位移场分量与介质的泊松比呈较弱的负相关,垂直位移场与介质的泊松比呈正相关,水平位移场与剪切模量呈正相关,垂直位移场与剪切模量呈负相关;2)模型介质的横向变化对同震位移场有较大影响,剪切模量的横向变化对地震位移场影响最大,且两者呈负相关,在垂直走滑断层地震中,保持断层一侧块体的介质参数不变、减半另一侧块体的剪切模量,剪切模量减半的块体中的最大垂直位移分量增大55.6%;3)倾角对同震位移场有重要影响。断层附近,倾角对位移场起控制作用,对于高倾角逆冲断层(60°～90°),上盘断层附近区域的水平位移场出现反向,反向区域的范围随倾角的增大而增大,当倾角为90°时,上盘水平位移场全部反向;断层倾角增大时,断层附近下盘的水平位移场的增大幅度较大。更多还原

【Abstract】 In order to quantify the effect of medium heterogeneities and the dip of the fault on the coseismic displacement,three-dimensional finite element numerical method was applied.The selected slip distribution models including finite rectangular strike,normal and reverse fault.The numerical simulation has given following results.1) For the vertical strike earthquake in the homogeneous and vertically layed mediums,the coseismic displacement slightly depends on the Poisson’s ratio,the relation between horizontally displacements and Poisson’s ratio is negative,and it is positive for the vertical displacements.The relation between horizontally displacements and shear modulus is positive,and it is negtive for the vertical displacements;2) In horizontally heterogeneous medium,the shear modulus plays a significant role on the surface displacements,the relation between shear modulus and displacement field is negative,in the case of the medium parameters on the right block of fault remain unchanged,the increase extent of maximum vertical displacements on the left block of fault reaches 55.6% and the shear modulus of the left block of fault halved.3)In the neighborhood of fault,the dip angle of fault dominate the coseismic displacements,as for the reverse fault earthquake with high dip(60°-90°),opposite direction region appears in the horizontal displacements on the hanging wall,the range of opposite direction region increase with dip-angle;and the increase extent of coseismic displacements on the foot wall is obvious.更多还原