地震波斜入射时水平层状场地的非线性地震反应

Nonlinear seismic response of horizontal layered site due to inclined wave

利用土层和半空间的精确动力刚度矩阵,可求解地震波斜入射,水平层状场地的动力响应,并可得到各土层的位移、应力及应变结果。结合等效线性化算法,可分析斜入射地震波(SH,SV,P)时场地的非线性地震反应。研究表明:入射角对地表的加速度峰值有重要影响,未必在波垂直入射时最大,可能有多个峰值;实际地震波入射角平均在60°左右,与斜入射SV波时峰值放大倍数最大值出现的角度基本一致,按垂直入射计算得到的结果可能不安全,表明了在场地非线性地震反应中研究斜入射的必要性。

Based on the exact dynamic-stiffness matrix of soil layers and half-space, the dynamic response of the horizontal layered site due to inclined waves is resolved. The displacement, stress and strain of every layer can be calculated. Based on the equivalent linear method, the nonlinear seismic response analysis of soil sites due to inclined waves （SH, SV and P） is presented. The study shows that the peak acceleration of ground motion is significantly influenced by the incident angle. The PGA is unnecessarily the largest for the vertical incidence. There can be multi-peak of ground motion due to inclined waves. The average incident angle of the actual seismic waves is about 60°, basically in agreement with the angle for the PGA due to incident SV waves. The results based on the vertical incidence may be unsafe. The necessity of oblique incidence in nonlinear seismic response analysis is shown.