库水位骤降作用下库岸滑坡形成机理研究

Study on reservoir bank landslide formation mechanism under the action of reservoir water level sudden drop

库水位骤降严重威胁着库岸边坡的稳定。基于饱和-非饱和土理论,采用渗流有限元法和稳定计算的Bishop法和Janbu法,计算确定不同水位骤降工况下渗流场及安全系数的演化情况。结果表明:库水位骤降会严重降低边坡的稳定系数,随着库水位下降速率的增大,稳定系数降低更多,此外,稳定系数随着库水位的逐渐平稳而上升。根据计算结果可以得出库水位诱发库岸滑坡的机理主要体现在孔隙水压激增及累积效应、渗流拖拽、渗透破坏效应、应力集中及转移效应。

Sudden drop of reservoir water level seriously threatens the stability of bank slope. Seepage finite element method,stability calculation Bishop method and Janbu method are adopted to calculate and determine seepage field and safety coefficient evolution condition under different water level sudden drop based on the saturated-unsaturated soil theory. The results show that sudden drop of reservoir water level may severely lower the slope stability coefficient,the stability coefficient is reduced to lower level with the increase of reservoir water level drop rate. In addition,the stability coefficient is increased with gradual stability of the reservoir water level. It can be concluded according to calculation results that the mechanism of inducing reservoir bank landslide by reservoir water level is mainly manifested in pore water pressure surge,cumulative effect,flow drag,seepage failure effect,stress concentration and metastasis effect.