库水位变动条件下岸坡渗流特性及稳定性研究

The Seepage Characteristics and Stability of Reservoir Banks Influenced by Water-level Variation

水电站库区水位周期性的升降是库岸边坡稳定性的一个重要影响因素。针对大岗山水电站右岸坝肩边坡在库水位变动条件下的稳定性条件问题,采用饱和-非饱和渗流理论研究边坡内部瞬态渗流场形成的规律,基于极限平衡方法,研究了库水位升降的不同阶段边坡全局稳定性与局部稳定性的演化规律。研究结果表明,渗流场影响范围的边坡局部稳定性随水位变化明显,库水位上升时,局部安全系数先减小后增大,库水位下降时,局部安全系数先减小后增大;边坡全局稳定性对库水位变动不敏感,库区最危险水位的确定,需结合全局与局部稳定性分析综合确定。

The cyclic fluctuation of water level is an important influence factor on the stability of reservoir bank slope.Based on the saturated-unsaturated seepage theory,aiming at the problem of the stability of right dam shoulder slope of Dagangshan Hydropower Station under the condition of reservoir water level changes,the formation of transient seepage field within the slope is studied.The global and local stability evolution of the bank slope is studied based on limit equilibrium method.The result shows that the local slope stability influenced by seepage field significantly varies obviously with the fluctuation of water level,that is,the local safety coefficient decreases firstly and then increases when water level increases;the local safety coefficient increases firstly and then decreases when water level drops.Due to the overall stability is not sensitive to water level variation,even if the local slope stability safety coefficient is higher than that of the overall safety factor.The determination of the most dangerous water level in the reservoir area should be combined with the overall and local stability analysis.