某多次开挖边坡治理失效机制分析

朝天中学滑坡位于朝天区朝天中学后山斜坡中下部,为一牵引式开挖型滑坡。2010年-2012年该滑坡由于两次开挖和极端降雨因素的影响,出现了多次失稳变形迹象。正确认识滑坡变形机制及演化过程是预防及治理滑坡地质灾害的重要前提,基于现场详细的调查和滑坡资料,并结合数值模拟方法,对朝天中学滑坡发生多次的变形失稳机制及其演化过程进行了分析,研究成果表明:首次切坡条件下,边坡沿原生结构中最"活跃"的基覆界面发生了牵引式堆积层滑坡失稳;在第二次切坡和部分加固手段实施后,由于坡体临空条件和自身结构的改变,促使坡内应力向深部转移,边坡也因此转为沿强-中风化接触面发生失稳的牵引式滑坡;鉴于前两次边坡失稳对坡体自身完整性的破坏,又逢区域性极端降雨,大量地表水的入渗致使坡体抗滑力和下滑力的此消彼长再次造成了边坡整体严重失稳。

Failure Mechanism Analysis of Several Excavation Slopes

Correct understanding of landslide deformation mechanism and evolution process is an important prerequisite for preventing and treating landslide geological disasters. Based on detailed field investigation and landslide data, the numerical simulation methods were adopted to analyze the mechanism and evolution process of multiple deformation and instability of Chaotian Middle School landslide. The results are as follows: under the condition of the first cut-off, the landslide along the most active overlying interface of the original structure occurs tractive accumulation layer. After the second cut-off and partial reinforcement measures are implemented, due to the change of the empty condition of the slope body and its own structure. As a result, the stress in the slope shifts to the depth, and the slope becomes a tractive landslide along the strong-moderate weathering interface. Considering that the destruction of the integrity of the slope caused by the first two instability of the slope, and the regional extreme rainfall, the infiltration of a large number of surface water causes the decline of the sliding resistance and the sliding force of the slope to cause the overall serious instability of the slope again.