白鹤滩水库初次蓄水对双河段岸坡稳定性的影响预测分析

以白鹤滩库区巧家县双河左岸土质岸坡为研究对象,通过野外详细调查、现场钻孔剪切试验以及SEEP&SLOPE模块耦合分析,针对该岸坡在未来蓄水后的稳定性问题进行预测分析.研究发现:双河左岸土质岸坡主要由残坡积角砾土组成,其对水敏感性较强,饱水后角砾土内聚力降低60.65％,内摩擦角降低40.0％,内聚力受影响程度大于内摩擦角.当水位由当前状态先升至765 m,再升至825 m时,渗流场反应明显,坡体稳定性系数由1.238降至1.098,再降至1.010,降幅先大后小,坡体由稳定状态过渡欠稳定状态后处于失稳临界状态.岸坡土体在库水作用下发生的结构损伤、强度衰减是岸坡稳定性恶化的主要原因,其变形趋势将由蠕滑变形向整体失稳破坏发展;在此过程中,库水的反压作用对于岸坡水下部分具有有利作用,促使岸坡受影响,高程段缩减.

Prediction and analysis of the influence of the first impoundment of Baihetan reservoir on the bank slope stability of Shuanghe river section

In this paper, the soil bank slope on the left bank of Shuanghe River in Qiaojia county of Baihetan reservoir area is taken as the research object, and the stability of the bank slope after the future impoundment is predicted and analyzed through the detailed field investigation, field drilling shear test and seep & slope module coupling analysis. It is found that the soil bank slope on the left bank of Shuanghe River is mainly composed of residual Deluvial breccia soil, which is highly sensitive to water. After water saturation, the cohesion of breccia soil decreases by 60.65%, the internal friction angle decreases by 40.0%, and the degree of influence of cohesion is greater than that of internal friction angle. When the water level first rises to 765m and then 825m from the current state, the seepage field response is obvious, the slope stability coefficient decreases from 1.238 to 1.098 and then to 1.010, the decline amplitude first increases and then decreases, and the slope is in the critical state of instability after the transition from the stable state to the unstable state. The structural damage and strength attenuation of the bank slope soil under the action of reservoir water are the main reasons for the deterioration of the bank slope stability, and the deformation trend will develop from creep deformation to the overall instability; in this process, the backpressure of reservoir water has a favorable effect on the underwater part of the bank slope, which makes the affected elevation section of the bank slope reduce.