斜坡震裂变形力学机制初探

PRELIMINARY STUDY ON MECHANICAL MECHANISM OF SLOPE EARTHQUAKE-INDUCED DEFORMATION

为了深入分析斜坡在地震中的震裂变形破坏形成机制,结合5.12汶川大地震造成的斜坡震裂变形和破坏现象的详细调查,采用有限元数值分析和振动台模拟实验相结合的研究方法,对单面和双面斜坡震裂变形的力学机制进行初步分析,认为地震中地震波的作用,将使坡体应力场出现重大变化,坡体尤其是坡面上将出现量值和方向不断调整变化的反复拉剪作用,是坡体(面)震裂变形甚至破坏的重要原因。分析还认为,拉剪作用有3种表现形式,即初动拉剪加速破裂效应、重复拉剪破坏效应和双坡共剪破裂效应,并结合实例对3种破坏效应进行分析。研究成果为预测震裂斜坡破坏提供了有力参考,也为灾后重建和防灾减灾提供了有力依据。

In order to analyze the formation mechanism of slope earthquake-induced deformation, combining with the detailed investigation on the earthquake-induced deformation and failure phenomenon caused by Wenchuan earthquake, the comprehensive analysis method, finite element numerical analysis and vibration table simulation experiments are adopted to analyze the earthquake-induced mechanism of single- and double-side slopes. The results show that the earthquake waves will make the stress field of slopes change significantly. The slope body, especially the grade surface, will generate repeatedly tensile and shear actions, of which values and orientations adjust continuously. These actions are significant reasons of slope failure. It is discovered that the shear actions has three representative forms, i.e. first motion tensile and shear acceleration rending effect, repeatedly tensile and shear rending effect, and double-side common shear rending effect. These rending effects have been found in practice. The results can provide references to forecast failure of earthquake-induced slope and reconstruction of powerful foundation after earthquake and hazard-resistant reduction.