【摘要】 运用震源位错模型 ,分析矩形垂直断层及倾斜断层走向滑动和倾向滑动的近场地震动场 ,以地表地震动的傅立叶振幅谱比为参量考察断层附近地震动空间分布的特点 .结果表明 ,断层附近的地震动强度主要受近旁子断层的控制 ,高强度的地震动分布在紧靠断层两侧有限的带状区域内 ,长周期分量受断层破裂传播方向性的影响 .走向滑动的方向性影响主要表现在垂直于断层走向的分量 ,倾向滑动则表现在平行于断层走向的分量 ,且深震在地面上引起的地震动强度分布比浅震要平缓 ,影响范围宽 .倾斜断层产生的地震动有明显的上盘效应 ,空间分布不对称 ,与观测结果相符 .最后给出了断层附近近场地震动强度分布拟合函数的表达式 ,并与美国的 1997统一建筑规范规定的近场因子作了比较 .更多还原

【Abstract】 Near fault strong ground motions of strike slip and dip slip of vertical and inclined rectangular fault in half space and layered half space is analyzed by dislocation source model. The Fourier spectra ratio of ground motion is adopted to study the characteristics of near fault ground motion. For both slip models, near fault strong ground motion with high amplitude is located in a narrow belt area along the projection of the fault on the ground and mainly controlled by the sub faults nearby. Directivity of strike slip fault is more dominant in long period for components perpendicular to the fault, and more dominant in long period for components parallel to the fault for dip slip fault. The deeper the location of the source is, the more slowly the amplitude of ground motion attenuates. There is obvious hanging wall effect in ground motion of inclined fault, and the spatial distribution of ground motion is asymmetric which coincides with observational data. Finally, a fitting function of spatial distribution for near fault ground motion is proposed and compared with near source factors of Uniform Building Code 1997 of USA.更多还原