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滑体与滑床之间地震波能量分布的差异性是引起基覆型滑坡失稳破坏的内因。为了从能量角度揭示基覆型滑坡的失稳机制,该文利用基于希尔伯特黄变换及边际谱理论,建立了基覆型滑坡地震失稳机制分析的能量方法。研究表明:(1)地震波在滑坡内自下而上传播过程中,滑带对高频部分的能量具有明显的衰减效应,对低频部分的能量具有显著的放大效应,且随着输入地震动强度的增大,由于剪应变的存在,滑带对低频部分地震波能量的放大效应逐渐减低;(2)地震波作用下基覆型滑坡滑带内的剪应变首先出现在滑带两端,并逐渐向滑带中部滑坡锁骨段移动;(3)滑坡失稳过程中滑体下部与滑床之间的相对位移差最大,滑体中部其次,滑体上部最小,表明滑体在失稳下滑过程中出现张拉裂隙,滑体结构变得松散。该研究成果能充分地揭示了汶川地震中大量出现的剥皮型滑坡的失稳机制。
The difference of the seismic energy distribution between the slide body and the slide bed is the internal cause of the instability damage of the foundation-cover type landslide. In order to reveal the instability mechanism of overlying landslide from the energy perspective, this paper uses the Hilbert-Huang transform and marginal spectrum theory to establish the energy method for the analysis of the seismic instability mechanism of the overlying landslide. The results show that: (1) During the propagation of the seismic wave from bottom to top in the landslide, the sliding band has a significant attenuation effect on the energy of the high frequency part and a significant amplification effect on the energy of the low frequency part. With the input seismic intensity Due to the existence of shear strain, the amplification effect of the sliding band on the low-frequency seismic energy gradually decreases. (2) Shear strain in the sliding zone of the base-coated landslide first appears at both ends of the sliding band under the action of seismic waves. (3) In the process of landslide instability, the relative displacement difference between the lower part of the slide body and the slide bed is the largest, followed by the middle part of the slide body, and the upper part of the slide body is the smallest, indicating that the slide body appears during the course of the instability slide Tension cracks, slide body structure becomes loose. The results of this study can fully reveal the instability mechanism of a large number of peeled landslides in the Wenchuan earthquake.