基于谱元法的地震动放大效应研究——以青川县斜坡为例

Investigations of Topographic Effects on Ground Motion Based on the Spectral Element Methods——A Study Case in Slopes of Qingchuan County

利用无人机航空遥感获取的高精度数据构建DEM模型,结合谱元法数值模拟技术对青川县区域动力放大效应进行探索,并与汶川地震诱发的地震灾害进行耦合分析。结果显示,斜坡地形存在对地震动幅度和持续时间有明显的放大作用。虚拟地震作用下,在东山、狮子梁、桅杆梁地形突出部位均出现峰值加速度放大的现象。合成数据分析表明,这种放大效应具有一定方向性,具体表现为水平向放大大于垂向,南北向放大大于东西向。根据对比,模拟结果与实测分析结果较为吻合,可为进一步开展斜坡地震动力评价提供参考依据。

We combine spectral element method(SEM)and high-resolution DEM model acquired by unmanned aerial vehicle remote sensing to investigate the amplification effects in Qingchuan area coupled with Wenchuan earthquake induced earthquake disasters.The simulation results show that the topography obviously enlarges the amplitude and duration of ground motion.The amplification of peak ground accelerations can be found in the protruding part of terrain under hypothetic earthquake.Synthetic records indicate the directionality of amplification effect that amplification in NE direction is more obvious than that in other directions.These conclusions are consistent with site monitoring results,which can provide a reference to future seismic dynamic evaluations of slope.