摘要
地震荷载作用下,断层两侧边坡稳定性一直是研究重点,本文主要探讨动态加载对不同位置坡体产生的地震动效应。首先,建立一个截面大小为500 km×100 km的有限元二维动态铲形断层模型,在地表断层两侧构建对称边坡来模拟滑坡地形。然后加载脉冲震源,通过对震源(深度为14 km)处节点指定加速度的方法,模拟计算地震发生后100 s内地震波传播对距断层分别为1 km,30 km及100 km的不同边坡震动产生的影响。结果显示:边坡震动强度随着震源距的增加而快速衰减,下盘的衰减比上盘更为强烈;距断层相同位置处,上盘比下盘振动幅度大;相同山体的不同位置上,水平方向振幅随断层距增大而衰减;垂直方向振幅,相同高程处的振幅相近,高程越高振幅相对减小;随着断层距的增加,山体的水平和垂直方向振幅都逐渐变小;震源距较远位置处的振幅比近震源位置小很多,说明近震位置处振动强度大,即在同等地质条件下,近断层的上盘区域更易发生滑坡。
Slope stability on both sides of seismogenic fault under seismic loading has been the focus of academic study.We mainly discuss the seismic effect of dynamic loading on slopes at different positions in this paper.First,we conduct a two-dimensional dynamic finite-element model of spade shaped fault with the size of 500 km×100 km.The symmetrical slopes on both sides of the fault are considered as the landslide terrain.Then,to simulate the earthquake effect,we set a pulse source at the depth of 14 km.The impact of seismic wave propagation on slopes with distance 1 km,30 km,and 100 km from the fault is analyzed in the first 100 s after earthquake happens.The results demonstrated that the vibration intensity decays rapidly with distance from the source,and that the decay rate at hanging side is more moderate than that of the footwall.With the same distance from the fault,the vibration amplitude of hanging side is larger than the footwall.In different locations of the same surface bulge,vibration amplitude decays with distance from the fault in horizontally.The vibration amplitude in vertical direction is similar to that of the same elevation position.The location with higher elevation has a rela-tively smaller amplitude.As the distance from the fault increases,amplitudes of surface bulge in horizontal and vertical direction become smaller gradually.The results show that in a place far away from the source,the amplitude of the point is much smaller than the near one which means at where the vibration intensity is larger.With the same geological setting,the near fault hanging side is easier to have landslide.
作者
惠红军
杨家英
赵永红
李小凡
Hui Hongjun;Yang Jiaying;Zhao Yonghong;Li Xiaofan(School of Earth and Space Sciences,Peking University,Beijing 100871,China)
出处
《地震学报》
CSCD
北大核心
2023年第4期695-705,共11页
Acta Seismologica Sinica
基金
国家自然科学基金项目(40821062,41274094和40872133)资助.
关键词
有限元
地震
铲型断层
边坡稳定性
finite element
earthquake
listric fault
slope stability
