主余震序列作用下边坡位移响应及地震动参数相关性分析

CORRELATION ANALYSIS OF SLOPE DISPLACEMENT RESPONSE AND SEISMIC PARAMETERS DUE TO MAIN-AFTERSHOCK SEQUENCES

边坡容易在地震作用下丧失稳定性,引发滑坡等次生灾害,造成严重的人员伤亡和经济损失。目前,关于边坡在地震作用下的位移响应研究主要关注主震作用,而没有充分考虑余震作用的影响。针对这一问题,该文挑选210条真实主余震序列作为边坡底部输入地震动,基于有限差分软件FLAC对边坡在主余震序列作用下的滑动永久位移进行了分析,采用增量位移比来量化余震对边坡位移响应的影响。进一步挑选15个地震动强度参数,分别研究了主震强度、余震强度、主余震强度与边坡主震位移、余震增量位移、主余震位移的相关性。研究结果表明:余震作用会对主震损伤边坡产生显著的竖向永久位移增量,该位移增量甚至可以大于主震位移。与边坡主余震位移的相关性最强的是主震强度;在所考虑的地震动强度参数中,主震反应谱加速度与加速度谱强度与主余震位移的相关性最强。最后,分别基于这两个最优地震动强度参数建立了主余震位移预测模型,模型精度较好。

Slopes are vulnerable during strong earthquakes,and earthquake-induced landslides have caused serious casualties and economic loss.At present,researchers mainly focused on the seismic slope displacements subjected to the mainshocks.However,the influence of aftershocks on slope stability is ignored.To address this issue,210 recorded main-aftershock sequences are selected in this study,which are subsequently used as input ground motions for the numerical analysis of slopes.Based on the finite difference software FLAC,the slope displacements caused by the main-aftershock sequences are analyzed,and the incremental displacement ratio is used to quantify the influence of the aftershocks on the slope responses.Fifteen ground motion intensity measures(IMs)are further selected,and the correlations of the IMs of mainshocks,of aftershocks,of the main-aftershocks with mainshock-induced displacements,of aftershock-induced incremental displacements,and of the mainaftershock induced total displacements are studied,respectively.The results show that aftershocks can produce significant vertical permanent displacement increments,some of which are even greater than the mainshockinduced displacements.The IMs of the mainshocks exhibit the strongest correlations with the main-aftershock induced slope displacements.Among the ground motion IMs considered,the spectral acceleration at the slope’s fundamental period and acceleration spectrum intensity of the mainshocks(Sa(Ts)Mand ASIM,respectively)exhibit the strongest correlation with the main-aftershock induced displacement.Finally,predictive models for the main-aftershock displacements are proposed based on the two optimal IMs identified,and the performance of the models is satisfactory.