库水位骤降对非饱和坝坡稳定性的影响

基于非饱和土体抗剪强度理论,采用极限平衡法,考虑非饱和非稳定渗流对坝坡稳定性的影响,通过体积含水量与基质吸力之间的非线性关系,模拟超静孔隙水压力的消散过程,将不同时段渗流分析结果导入稳定分析模块计算其安全系数的变化。选取某黏土心墙坝,模拟其在不同灌溉条件下的渗流状况及上游坝坡稳定性。计算结果表明:库水位骤降引起坝坡安全系数的降低,但随着超静孔隙水压力的消散,坝坡稳定性逐渐增强,降水速度越快,坝坡安全系数越低。

Influence of rapid drawdown of reservoir level on stability of unsaturated dam slope

The reduction of the safety factor caused by the rapid drawdown of the reservoir level leads to the instability of the dam slope.Therefore,it is important for reservoir flood control and irrigation to research influences of different drawdown velocities of the reservoir level on the dam slope stability.With consideration of the effects of unsaturated transient seepage on the stability of the dam slope,the process of the excess pore water pressure was simulated using the limit equilibrium method based on the shear strength theory for unsaturated soil and the nonlinear relationship between the volume water content and matric suction.Then,the seepage analysis results for different times were incorporated into the stability analysis module to calculate the safety factor of the dam slope.The calculated results show that rapid drawdown of the reservoir level can result in a decrease of the dam slope safety factor,and the faster the drawdown of the reservoir level is,the smaller the safety factor will be.However,the stability of the dam slope was enhanced with the dissipation of excess pore water pressure.The simulation method can provide a theoretical basis for determining the flood discharge during reservoir flood control operation.