库水位涨落对库岸滑坡稳定性的影响

三峡水库正常蓄水后, 库水位在175~145m之间周期性波动, 滑坡地下水渗流状态将会发生较大的改变, 可能导致滑坡失稳.因此, 研究库水位周期性波动下滑坡的稳定性具有十分重要的意义.提出了土水特征曲线的多项式约束优化模型和采用饱和-非饱和渗流数值模型.以赵树岭滑坡为例, 利用有限元数值计算了库水位在175~145m之间波动下地下水渗流场, 将计算得到的孔隙水压力用于滑坡的极限平衡分析, 探讨了库水位上升和下降对库岸滑坡稳定性的影响.研究表明: 多项式优化模型可以很好地拟合非饱和土的土水特征曲线; 库水位上升时滑坡稳定性系数总体逐渐增大, 库水位下降时滑坡稳定性系数总体逐渐减小; 无论是库水位上升还是下降到库水位155m时, 其稳定性系数最小; 同一库水位下, 库水位上升时的稳定性系数比下降时的稳定性系数大. 

The Influence of Water Level Fluctuation on the Bank Landslide Stability

The water level will periodically fluctuate between 145 and 175m since normal water level storage in Three Gorges reservoir, while the ground water seepage of landslide will be subject to great changes, which may lead to landslide instability. So it is of great significance to study the influence of water level fluctuatation on the bank landslide stability. In this paper, a polynomial constrained optimized model for soil-water characteristic curve is put forward and the saturated-unsaturated seepage flow numerical model is applied. In addition, Zhaoshuling landslide is taken as an example, water seepage fields are simulated by using finite element method with the water level fluctuation between 145 and 175m. The transient pore water pressures are used for limit equilibrium analyses of landslides with taking the effects of suction on shear strength of unsaturated soils into consideration. Then we discuss the effect of the fluctuation of water level in Three Gorges reservoir on the bank landslide stability. The result shows that a polynomial constrained optimized model may well fit the characteristic curve of soil and water of unsaturated soil. The stability coefficient increases gradually in general along with reservoir water level rise and the stability coefficient decreases gradually in general along with the fall of reservoir water level. However, when the reservoir water level reached 155m, whether it rises from 145m or falls from 175m, the stability coefficient is smallest; while the stability coefficient in period of reservoir water level rising from 145m to 175m is larger than that in period of falling from 175m to 145m.