白鹤滩库区小江碎石土岸坡库水作用稳定性规律分析

水库蓄水是导致山区水库的地质灾害频发的主要原因之一。通过现场调查、物理力学性质试验和数值模拟分析对白鹤滩库区小江碎石土岸坡的蓄水稳定性进行了研究。研究结果表明:在库水上升阶段坡体内浸润线呈“内凹”状,库水快速下降阶段坡体浸润线呈“外凸”状,坡体内部渗流场始终处于不断调整状态,但浸润线变化始终滞后于库水位的变化。在库水上升阶段,岸坡受到向坡内的渗透压力、容重增加及土体浸泡软化等因素影响,岸坡稳定性相比于天然状态略有降低。在水位下降阶段,土体因受到长时间的浸泡软化作用,抗剪强度已经降低,而坡体因渗流作用产生的指向坡外的渗透压力又会增加岸坡的下滑力,降低岸坡的稳定性,使岸坡失稳破坏。

Analysis on Reservoir Water Stability Law of Gravel Soil Bank Slope of Xiaojiang River in Baihetan Reservoir Area

Reservoir impoundment is one of the main reasons for the frequent occurrence of geological disasters in mountain reservoirs. The water storage stability of the gravel bank slope of Xiaojiang River in the Baihetan reservoir area was studied by field investigation, physical and mechanical property test, and numerical simulation analysis. The results show that in the rising stage of reservoir water, the saturation line of the slope body is "concave" shape, and in the rapid falling stage of reservoir water, the saturation line of the slope body is "convex" shape, and the seepage field of the slope body is always in a state of constant adjustment, but the change of the saturation line always lags behind the transformation of the reservoir water level. In the rising stage of reservoir water, the stability of the bank slope is slightly lower than that of the natural state due to seepage pressure, an increase of bulk density, and soil softening. In the stage of drawdown, the soil is soaked for a long time, and the shear strength decreases; In addition, the seepage pressure outside the slope caused by seepage increases the sliding force of the bank slope, reduces the stability of the bank slope, and makes the bank slope unstable.