摘要:
三峡大坝自2003年蓄水以来，库区形成大量涉水滑坡。长江三峡库区的浮托减重型滑坡随库水位升降，变形非协调性增加，此类滑坡变形与库水位关系的不明确性，为其监测预警预报工作带来困惑。以木鱼包滑坡为研究对象，通过全自动GPS变形监测系统获取的滑坡监测资料，结合多次的野外考察、15年专业监测和库水位升降等资料进行分析，运用有限元软件Geo-studio进行数值模拟，模拟库水位以不同速率在175 ~ 145 m间升降下对滑坡稳定性的影响。研究表明：(1)库水位由145 m升至175 m的过程中，滑坡的稳定系数变化为先减后增再减，库水上升速率越大，前期稳定系数减小的时间段越小，随后稳定系数增加的速率也越快；(2)在库水位由175 m下降到145 m的过程中，整个稳定系数变化趋势为先减小后增大，呈“V”字形，存在一个最危险水面，不同的库水下降速率对应的最危险水面高度也不一样,库水位以0.4，0.6，0.8，1.0，1.6 m/d的速率下降时对应的最危险水位分别在169.8，167.8，162.6，162.0，162.2 m左右；(3)木鱼包滑坡作为三峡库区典型的浮托减重性滑坡，在库水位大幅度及周期性升降的影响下，一直保持着蠕滑状态，平均日位移量为0.4 mm/d，目前处于基本稳定状态。所得结论对三峡库区浮托减重型滑坡预警预报工作有一定的参考与借鉴意义。
Abstract:
Since the impoundment of the Three Gorges Dam in 2003, a large number of wading landslides have occured in the reservoir area. In the three Gorges Reservoir area of the Yangtze River, the buoyancy weight loss landslide increases with the rise and fall of the reservoir water level. The uncertainty of the relationship between the deformation of the landslide and the reservoir water level brings confusion to the monitoring, early warning and prediction of this kind of landslide. In this paper, the Muyubao landslide is taken as the research object, the landslide monitoring data obtained by automatic GPS deformation monitoring system are analyzed in combination with many field investigations and professional monitoring and reservoir water level rise and fall data of 15 years. The finite element software Geo-studio is used to simulate the influence of the reservoir water level on the stability of the landslide under the condition of rise and fall of the reservoir water level between 175 m and 145 m at different rates. The results show that (1) during the process of reservoir water level rising from 145 m to 175 m, the stability coefficient of landslide changes in the trend of decreasing first, then increasing and then decreasing, and the larger the rising rate of reservoir water, the shorter the time of stability coefficient decreasing in the early stage. (2) In the process of the reservoir water level falling from 175 m to 145 m, the whole stable coefficient changes from decreasing at first and then increasing, showing the ‘V’ shape, and there is the most dangerous water surface. The height of the most dangerous water level varies with the rate of decline of reservoir water. When the reservoir water level decreases at the rate of 0.4,0.6,0.8,1.0,1.6 m /d, the corresponding most dangerous water levels are about 169.8,167.8,162.6, 162.0， 162.2 m. (3) The Muyubao landslide is a typical floating body weight reducing landslide in the Three Gorges Reservoir area. Under the influence of large amplitude and periodic rise and fall of reservoir water level, the Muyubao landslide keepsa creep state all the time, and the average daily displacement is 0.4 mm/d. At present, it is in a basically stable state. The conclusion can be used for reference in the early warning and prediction of floating support and weight loss landslide in the three Gorges Reservoir area.
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