云盘头滑坡变形破坏机制研究

Simulation on the Deformation and Failure Mechanism of Yunpantou Landslide, Guizhou

缓倾顺层岩质边坡由于其岩层倾角较缓,具有不易察觉其失稳且识别难度大的特点。以一个典型的缓倾顺层岩质边坡(贵州云盘头滑坡)为例,基于工程地质勘察,建立边坡地质模型,并结合底摩擦试验、二维离散元和有限元模拟等方法,探讨云盘头滑坡的变形破坏机制。结果表明:云盘头滑坡的变形破坏过程可分为微裂纹发育阶段、裂纹拓展阶段、滑体变形阶段与完全破坏阶段,并在坡脚存在关键块体;滑坡形成的主要原因是,坡体经过开挖导致软弱夹层出露,坡体内部发育垂直于软弱夹层的拉裂纹并将滑体分割成块体,随着坡脚关键块体向临空面滑移,后部次级块体随之移动并产生多米诺骨牌效应导致坡体发生整体滑移,变形模式属于典型的滑移-拉裂式。研究成果为探究缓倾顺层岩质边坡的失稳破坏有现实意义。

The instability of gently inclined bedding rock slope is difficult to be recognized and detected because of its gentle dip angle.The Yunpantou landslide in Guizhou,China,is a typical gentle dip bedding rock slope with four sets of weak intercalated layers in the slope.Probing into its deformation and failure mechanism is of practical significance for the research of gently inclined bedding rock slope failure.In this paper,the deformation and failure mechanism of Yunpantou landslide is examined by establishing a geological structural model based on engineering geological survey in association with various approaches such as bottom friction test,two-dimensional discrete and finite element simulations.Results reveal that the deformation and failure process of landslide can be divided into four stages,namely,microcrack growth stage,crack propagation stage,landslide deformation stage,and complete destruction stage.Key blocks exist in slope toe.The main causes of the landslide can be depicted as the exposure of weak intercalated layers resulted from excavation,and tension cracks perpendicular to the weak layers developed and divided the sliding body into blocks;with the sliding of key blocks in slope toe towards the free face,secondary blocks moves correspondingly and generates a Domino effect leading to the integral sliding of slope,which,therefore,is a typical sliding tension landslide.