顺层缓倾型水库滑坡稳定性物理模拟试验研究——以向家坪滑坡为例

PHYSICAL SIMULATION MODELING FOR STABILITY ANALYSIS OF RESERVOIR LANDSLIDE IN GENTLY UNDERDIP SLOPES: A CASE STUDY OF XIANGJIAPING LANDSLIDE

深入研究顺层缓倾型水库滑坡的变形破坏规律、影响因素以及失稳条件,以三峡库区向家坪滑坡为典型实例,基于相似理论建立地质物理模型,考虑水位升降、降雨(含汛期)等诱发因素,通过监测滑坡模型的位移、土压力及孔隙水压力的时空演化规律,掌握滑坡的变形特征和规律。结果表明:库水位上升,坡体前缘不断被浸没,致使土体结构松散,前缘发生滑移式滑塌;库水位下降,其位移、土压力和孔隙水压力在坡体中部和后缘均无变化,但前缘破坏范围扩大,延伸至中部;库水位的独立变动仅影响下伏滑床水位,但当其与后缘的基岩裂隙水耦合作用时,可改变滑床的承压水头;汛期降雨较小,对滑坡稳定性影响不大,仅土压力和孔隙水压有小幅度的变化,没有位移变形;在暴雨作用下,中部和后缘先后发生变形,土体应力累积和释放。库水位下降时,强降雨将改变坡体原始应力状态,坡体产生微小变形;在极端条件下向家坪滑坡发生滑动的可能性较大,库水位的下降、暴雨和后缘水位相互耦合作用导致坡体变形破坏。研究结果可为库区地质灾害防治和减灾提供科学依据。

The study of deformation law,influence factors and failure conditions of reservoir landslide in gently under-dip slopes is carried out by physical modeling. The Xiang Jiaping landslide in the Three Gorges Reservoir region is used as a case example. Based on the similarity model,considering the factors such as water level fluctuation and rainfall（ including flood season）,this paper analyzes the deformation characteristics and laws of landslide with monitoring the spatiotemporal evolution of displacement,soil pressure and pore water pressure. The results show that the reservoir level rises and the front edge of the slope is continuously submerged,resulting inloosening of the soil structure and slipping in the leading edge. With decreases of reservoir water,change of displacement,soil pressure and pore water pressure were not monitored in the middle and trailing edge of the slope,but the failure of the leading edge extended backward to the middle of the slope. The independent change of reservoir water level only affects the water level of the slide bed,but when it is coupled with the bedrock fissure water of the trailing edge,the pressure of the bed can be changed. During flooding season,the soil pressure and the pore water pressure have little change,and there is no displacement deformation,because of low rainfall intensity.Under the heavy rain,the soil pressure accumulates and releases,which leads to the deformation of the middle and trailing edge of the slope. When the reservoir water level drops,the heavy rainfall would change the original stress state of the slope,and the slope would produce small deformation. Under extreme conditions,the coupling of decline of reservoir water,rainfall and the trailing edge water level can result in deformation of the slope,which makes the failure possibility of Xiang Jiaping landslide larger. The results can provide scientific basis for geological disaster prevention and mitigation in reservoir area.