层状半空间中洞室对入射平面P波的放大作用  

Amplification of plane P waves by a cavity in a layered half-space

作　　者：梁建文[1] 尤红兵[1] 

机构地区：[1]天津大学土木工程系,天津300072

出　　处：《地震工程与工程振动》2005年第2期16-24,共9页Earthquake Engineering and Engineering Dynamics

基　　金：国家自然科学基金项目(50378063);教育部优秀青年教师资助计划项目

摘　　要：文中利用间接边界元法,在频域内求解了层状弹性半空间中洞室对入射平面P波的放大作用问题。通过自由场反应分析,求得假想洞室边界上各单元的应力响应。在洞室边界各个单元上施加虚拟分布荷载,求得位移和应力的格林函数。根据应力边界条件确定虚拟分布荷载,将自由场位移响应和虚拟分布荷载产生的位移响应叠加起来,即得到问题的解答。比较了层状半空间和均匀半空间中洞室对入射平面P波的放大作用,结果表明,层状半空间情况有可能导致较大的地表位移幅值,尤其是对于较低频率入射波。Amplification of P waves by a cavity in a layered half-space was analyzed by indirect boundary element method in frequency domain. The free-field response was calculated to determine the stresses on the line which will form the surface of the cavity. Then fictitious distributed loads were applied on the same line in the free field to calculate Green’s functions for the displacements and stresses. The amplitudes of the fictitious distributed loads were determined by the boundary conditions of stresses, and the displacement response arising from the waves in the free field and from the fictitious distributed loads were summed up to obtain the solution. The amplification of the incident P waves by a cavity in a homogeneous half-space and a layered half-space were compared, and numerical results showed that larger surface displacement amplitude may be resulted in the case of layered half-space, especially for incident low-frequency waves.

关 键 词：层状半空间 洞室 平面P波 散射 放大作用 

分 类 号：P315.3[天文地球—地震学]