震裂-滑移式崩塌形成机制及变形规律研究

Research on formation mechanism and deformation law of shattering-sliding collapses

以四川省S303线卧龙至巴郎山段K70＋340~K70＋388处崩塌为研究对象,采用地质力学分析和UDEC离散元模拟相结合的方法,揭示了震裂-滑移式崩塌形成机制及其变形破坏规律。结果表明：该类型崩塌主要发生在有陡倾结构面的顺层岩质斜坡;地震波对斜坡岩体主要为拉剪破坏,并呈现出坡顶和坡面处拉应力大于坡体内部的规律;地震力对斜坡的影响表现出顶部较下部、坡面较坡内变形快、变形量大的特点;随地震波加速度的幅值的增大,斜坡动力响应也越强烈,崩塌体的位移也越大;震裂破坏过程可以归纳为6个阶段,即（1）地震作用下岩体的损伤和拉张裂缝的形成;（2）拉张裂缝的拓展和软弱滑移面的贯通;（3）崩塌体整体震散和局部岩块的滑移;（4）局部岩块失稳,产生岩体的坠落、弹射、抛射和滚落现象;（5）岩体整体产生坠落、弹射、抛射和滚落;（6）崩塌体趋于稳定。该问题的研究不仅可以为地质灾害的分析提供新方法,而且对震区防灾、减灾具有一定的指导意义。

This paper investigates the formation mechanism and deformation law of earthquake-induced shattering-sliding collapses induced by studying the collapse at K70＋340-K70＋388 of S303 highway from Wolong to Balangshan in Sichuan province, using the combination of geomechanical method and the simulation of discrete element method UDEC. It is shown that： these collapses mainly occur in bedding slopes with steep joints; the seismic wave leads to a tensile-shear failure to the slope; and the tensile stress at dome of the slope is greater than that inside the slope; deformation induced by seismic force is found to be faster and greater at the upper and dome of the slope than that at the lower and interior of slope; the higher amplitude of seismic acceleration is, the greater slope dynamic response is, and the larger displacement of collapse mass. The failure process of shattering-sliding collapse can be divided into six stages, 1） rock mass damage and tensile fractures formatting under earthquake; 2） tensile fractures expansion and coalescence of weak slip plane; 3） the whole slump-mass scattered and local rocks slip; 4） local rocks fall, ejection, mass ejection and tumble; 5） rock mass fall, ejection, mass ejection and tumble; 6） slump-mass tends to be stability. Therefore, this research provides not only a new method for geological hazard analysis, but also a significant guide to disaster prevention and mitigation in earthquake region.