水位升降条件下牵引式滑坡离心模型试验

自三峡水库蓄水后，库区地质灾害频发，研究库水位升降条件下的库岸边坡稳定性与破坏模式日益重要。以三峡库区云阳县凉水井滑坡为原型，基于长江科学院CKY?200土工离心机，结合滑坡区工程地质概况，模拟制作了这一典型库岸滑坡的简化模型。采用高速相机、激光位移传感器、孔隙水压力传感器、土压力传感器等监测手段，在模型试验中实现了对边坡前缘水位高程及升降的控制，获取了试验过程中坡体水平位移和沉降、孔隙水压力、土压力值的变化规律，得到以下结论：试验从开始至加水阶段结束，模型位移以竖直方向为主，而在排水阶段则水平方向位移远大于竖直方向；试验过程中，在库水位上升与骤降作用下，首先在前缘产生裂隙，并逐渐向中部、后缘扩展，随后在中部产生较大变形，出现局部滑移，模型总体破坏形式呈牵引式破坏模式；试验结束时，模型自后缘起体积含水率逐渐增大；在水位上升期间，模型变形相对较小，主要滑移出现在水位下降期间，因此，该滑坡为动水压力型，产生变形破坏主要是由于动水压力效应所致。试验揭示了库岸牵引式滑坡在库水位升降条件下的破坏模式和变形失稳机制，为库区滑坡的防治提供了重要依据。

Centrifugal test on retrogressive landslide influenced by rising and falling reservoir water level

Geological disasters occurred frequently in the reservoir area since the Three Gorges reservoir was built up, which highlights the importance to study the stability and failure mode of reservoir bank under the condition of reservoir water level fluctuation. A method to evaluate the slope stability by centrifugal test is introduced with Liangshuijing landslide as a testing case. Soil slope models considering geological conditions of the Three Gorges are also constructed. Through the techniques of digital photography, laser displacement sensor, pore water and soil pressure sensor, controlling of drawdown and charging of reservoir is implemented in the test, and a series of important test data such as pore water pressure, displacement, pore water pressure and soil pressure is obtained. Results indicate that the model displacement is mainly in the vertical direction from the beginning to the end of the water adding stage, and the horizontal displacement is much larger than that in water falling stage. With the rising and plunging of the reservoir water level during the experiment, crack formation appears at the leading edge first, then gradually extends at the middle and trailing edge. In this process, large deformation is generated at the middle edge and localized slip appears. In general, failure pattern of the model shows the trend of retrogressive mode. At the end of the experiment, volumetric water content gradually increases from the trailing edge. During the rise of water level, model deformation is relatively small. The main deformation occurs during the decline of water level. Therefore, the landslide is a dynamic-water-pressure type. The deformation and failure are mainly due to the dynamic water pressure effect. The failure mode and the mechanism of deformation instability under the condition of reservoir water level fluctuation are revealed by the experiment, which provides an important basis for the prevention and control of landslide in the reservoir area.