地震动强度对黄土地震滑坡后壁形态的影响

Influence of seismic intensity on the shape of loess landslide scarp

震害表明,不同强度地震动诱发的黄土地震滑坡形态有较大差别。利用野外调查数据统计了1920年海原特大地震诱发滑坡后壁倾角的平均值,运用颗粒流软件PFC^(2D)计算得到了不同地震动强度下滑坡后壁的形态特征,最后根据野外调查实例进行了验证。结果表明:(1)地震动强度是造成滑坡后壁形态差异的重要影响因素。在其他条件一定的前提下,地震动越大,滑坡后壁倾角越小,滑坡后壁位置越靠近原始斜坡的高位;(2)滑坡后壁具有坡度大、海拔高、人为改造难度大、自身含水量较低、原状黄土结构性较好等特征,稳定性较强,在野外调查中可以利用滑坡后壁倾角和滑坡后壁的形态特征快速区分诱发滑坡的历史地震。

The historical earthquake damage shows that the forms of landslides induced by different earthquake intensities are significantly different.Based on the field investigation of landslide scarp shape,the movement process of landslide is simulated by PFC^(2D),and the shape characteristics of landslide scarp under different seismic intensity are obtained.The results show that:(1)the intensity of ground motion is an important factor that causes the shape difference of landslide scarp.Under certain other conditions,the larger the ground motion is,the smaller the back wall angle of the landslide is,and the closer the occurrence position is to the high position of the original slope;(2)the landslide scarp has the characteristics of large slope,high altitude,difficult artificial transformation,low water content,and good structure of undisturbed loess.It has strong stability.In the field investigation,the dip angle of landslide scarp and the morphological characteristics of the landslide scarp can be used to quickly distinguish the historical earthquakes that induce the landslide.