地震滞后滑坡的破坏机理及防治措施研究

由于地震的强烈震动作用,使一些岩质斜坡内部形成了塑性贯通区,易使斜坡成为不稳定斜坡,遭遇外力作用后就有可能形成地震滞后滑坡。以汶川地震中的某不稳定斜坡为研究对象,利用大型有限元软件ANSYS建立数值模型,研究其地震作用下的动力响应。数值模拟的结果表明:地震波穿越节理面后,发生了较大变化,使节理面上下岩体运动方式不同;岩桥在地震作用下,内部剪应力和拉应力波动较大,最终导致了岩桥的塑性贯通;层间节理位移分布很不均匀,动力响应也有较大不同。最后,根据工程地质勘察结果和不稳定斜坡的特点,确定了潜在的滑动面,并提出了裂缝注浆和削坡减载的治理措施。

Failure Mechanism and Prevention Measures of Lagged Earthquake-induced Landslide

Under strong earthquake action, plastic zone penetrates through rock slope and makes it unstable. Encountered with external forces these unstable slopes are likely to become lagged landslides. In the present research we established a numerical model using finite element software ANSYS to simulate an unstable slope after Wenchuan earthquake. The simulation revealed that joint surfaces changed a lot after earthquake waves passed through, the movements of rocks on two sides of the joint surface were different; the internal shear stress and tensile stress of rock bridge fluctuated heavily, which induced the penetration of plasticity; the contact sliding distance distributed very unevenly, and the dynamic responses of different positions of joints were quite different. Finally, according to engineering geological survey results and characteristics of unstable slope, we identified the potential sliding surface, and proposed treatment measures including crack-grouting and slope-cutting.