三峡库区黄泥巴蹬坎滑坡变形机制

Deformation Mechanism of Huangnibadengkan Landslide in Three Gorges Reservoir Area

[目的]研究黄泥巴蹬坎滑坡的变形规律及失稳机制,旨在为库区同类型滑坡的研究提供借鉴。[方法]分析该滑坡的宏观变形特征,结合专业监测数据,研究其变形规律及失稳机制,并运用数值模拟计算研究库水位下降的致滑机理。[结果]黄泥巴蹬坎Ⅰ号滑体变形严重,分别于2007年4—6月,2009年4—6月,2012年4—6月发生加速变形,且加速变形速率逐次呈快速增长趋势。库水位下降对该滑坡稳定性的影响表现为坡体外部卸荷效应和内部动水压力推动作用。一方面,库水位下降使得指向坡内的静水压力消失,导致抗滑力减小。另一方面,库水位下降引起坡内地下水位下降,地下水沿滑带方向渗流,产生的动水压力推动滑坡向外发生变形。[结论]目前黄泥巴蹬坎滑坡处于欠稳定状态,库水位下降加之连续强降雨是导致黄泥巴蹬坎滑坡变形失稳的主要因素。

[Objective]Studying the deformation rule and failure mechanism of Huangnibadengkan slope in order to achieve accurate prediction of landslide and provide reference for similar type of landslides research.[Methods]Through the analysis of its macroscopic deformation characteristics and based on professional monitoring data,the deformation rule and failure mechanism of this slope was studied.Meanwhile,slide mechanism mainly caused by water level falling is analyzed using the numerical calculation.[Results]Serious deformation happened in slide massⅠ of Huangnibadengkan slope,which experienced accelerating deformation for three times,occurred in April to June in 2007,2009 and 2012,respectively.The effects that reservoir water drawdown makes on this landslide are considered as two aspects：unloading on slope surface and internal hydrodynamic pressure.That means,on one hand,the horizontally slope-inward hydrostatic pressure disappears,as a result,the resistance force will decrease;on another hand,the underground water level drops triggered by reservoir water drawdown,will result in outward deformation of the landslide pushedbyhydrodynamic pressure.[Conclusion]The Huangnibadengkan landslide is in an unstable state at present,and falling of reservoir water level and continuous heavy rain are proved to be the main factors that lead to the deformation of this landslide.