刘家湾滑坡特征及成因机制探讨

刘家湾滑坡位于青川东河口红光乡刘家湾,为汶川地震触发的特大型岩质山体滑坡。野外调查结果表明,该滑坡堆积体与一般汶川地震滑坡运动堆积体迥异的是滑体在沿碳质板岩与白云岩划分带破坏溃滑后,滑源区又沿白云岩风化卸荷带触发了二次溃滑,形成二级堆积平台的形态且以不同岩性区分,在岩性划分带及风化卸荷带呈现出明显的动力破坏特性。通过对该滑坡堆积体进行岩体物理力学试验及波速测试研究表明,该滑坡由白云岩、碳质板岩及千枚岩组成的内硬外软岩质边坡具有明显的量化差异特性,强震条件下差异岩性组合边坡岩层接触面的动力突变效应耦合凸出地形是导致该边坡破坏的主要因素。近一步研究显示该滑坡运动可大致分山体震裂阶段、地质分界面应力突变阶段、高速溃滑阶段、碎屑流堆积阶段、二次溃滑堆积5个动力过程。

DISCUSSION ON GENETIC MECHANISM AND GEOLOGIC CHARACTERISTIC OF LIUJIAWAN LANDSLIDE

Liujiawan landslide is at Donghekou Hongguang town of Qingchuan county. The large rock landslide is triggered by Wenchuan earthquake in 2008. Field survey results show that the landslide deposit is different to the general Wenchuan earthquake landslide deposit. The landslide has the first destruction collapse along with division zones of carbonaceous slate and dolomite. The slip source region triggers a secondary collapse along with the dolomite weathering unloading zones. It takes the shape of two stacked stacking platforms and distinguishes between different lithologies. The lithology and weathering unloading belt show a significant power failure characteristic. The rock physical science experiment and wave velocity test of landslide deposit studies show that the hard outer soft rock slope is composed of dolomite, carbonaceous-slate and phyllite and has obvious differences in characteristics to quantify, differences lithologic of rock slope contact surface. Under earthquake conditions, dynamic mutation effect coupling projections terrain is the main factor that caused the slope failure. Closer study shows that landslide movement can be roughly divided into the following five dynamic processes including shattered mountain stage, geological interfacial stress mutation, high speed collapse, sturzstrom and accumulation, and secondary collapse slip stacking.