库岸边坡渗流及稳定性分析

库岸边坡常因受到库水位周期性波动的作用而失稳。传统的饱和土渗流及稳定分析方法无法正确描述水位升降过程中岸坡内孔压场的动态变化及其对岸坡安全系数的影响规律。本文从非饱和土的渗流和抗剪强度理论出发，分析了水位升降时土质岸坡的渗流规律及其稳定性的变化规律。通过选取典型的土性参数，对黏土、粉土和均质砂岸坡进行饱和-非饱和渗流分析，得到水位升降过程中岸坡内孔隙水压力场，再引入极限平衡方法，考虑基质吸力对非饱和土抗剪强度及岸坡安全系数的贡献，进行岸坡稳定性分析。分析表明，土体的饱和渗透系数和土水特征曲线共同决定了水位升降时岸坡内孔隙水压力的大小及分布，水位升降情况下岸坡安全系数的变化规律也与岸坡土体的渗透特性有关。

Seepage and stability analysis of bank slopes

Failure of bank slopes is often caused by seasonal water level fluctuation of reservoirs.The analyses of seepage and stability using the theory for saturated soil are often inadequate because they cannot describe the changing pore pressure and its influence on the factor of safety of bank slopes. Based on the theory of seepage and shear strength of unsaturated soils, the seepage and stability analysis of clay, silt and fine sand banks with representative parameters were carried out. The obtained pore-water pressure fields were then imported into the limit equilibrium analysis program to evaluate changes in the factor of safety with changing reservoir level. In limit equilibrium analysis, the contribution of matric suction to shear strength was considered by using Fredlund's shear strength equation for unsaturated soils. The results show that the value and distribution of pore-water pressure are determined by the saturated coefficient of permeability and the soil-water characteristic curve.Changes of the factor of safety during water level fluctuation are mainly determined by these parameters as well.