水位涨落作用下藕塘滑坡响应特征模型试验研究

MODEL TEST RESEARCH ON RESPONSE CHARACTERISTICS OF OUTANG LANDSLIDE UNDER WATER LEVEL FLUCTUATION

藕塘滑坡是三峡库区结构复杂的巨型古滑坡之一,由多个次级滑体和滑面组成,大坝蓄水运行以来,滑坡出现复活迹象,对周边数千人的生命财产安全构成威胁。为明确藕塘滑坡在库水位涨落作用下的响应特征、变形破坏模式和机制,以物理模型试验为手段,通过制配滑坡模型试验材料,精确控制试验中库水位涨落条件,实现了藕塘滑坡变形失稳过程试验模拟,并从试验角度探讨了藕塘滑坡响应特征和力学机制。得到以下结论:库水涨落速度越快组成滑坡的3个次级滑坡产生的变形越大,库水位下降造成的滑坡变形明显大于库水位上涨和稳定状态;库水位涨落影响主要集中于第一期次滑坡区域,当库水位快速下降时第一期次滑坡坡脚局部发生牵引式崩滑的风险大;第一期次滑坡变形造成其后的第二期和第三期次滑坡稳定性下降,随之发生变形;藕塘滑坡为动水压力型滑坡,滑坡在库水位涨落作用下发生整体沿基岩面滑移破坏的可能性不大,变形失稳模式表现为第一期次滑坡前缘的局部崩滑。试验揭示了该类滑坡在库水位涨落作用下的响应特征和变形破坏机制,可为类似滑坡的研究提供参考。

The Outang landslide is a giant complex ancient landslide in the Three Gorges Reservoir Region.It consists of multiple sliding zones and multiple sliding masses.Some obvious creeping slip of the landslide were found after the impoundment of the Three Gorges Reservoir.The landslide has a great threat to thousands of people’s lives and properties nearby.In order to clarify the response characteristics and the failure mechanism of the landslide under the influence of water level fluctuation,a model test is done.The model test material development and the accurate control of the water level fluctuation can simulate the process of instability of the Outang landslide.Response characteristics and mechanical mechanism of the Outang landslide are discussed.Results indicate that the fast the speed of the water level fluctuation,the bigger deformation of the three phase sliding masses which compose Outang landslide.The influence of water level fluctuation is concentrated in the zone of the first phase mass.The rapid drawdown of the water level result in deformation of the slope,which makes the retrogressive sliding possibility of Outang landslide larger.The stabilities of the second phase mass and the third phase mass decline after the deformation of the first phase mass.Outang landslide is the hydrodynamic pressure landslide.The whole Outang landslide mass is less likely to destroy along the bed rock surface under water level fluctuation.The major failure mode of the Outang landslide under the water level fluctuation is the type of local buckling failure in the leading edge of the first phase sliding mass.This test reveals response characteristics and instability mechanism of the landslide under water level fluctuation,which provides reference for researching this kind of landslide.