黏土心墙坝库水位骤降联合降雨上下游坝坡渗透稳定性数值模拟

Numerical simulation of seepage stabilities of upstream slope and downstream slope of dam with clay core-wall during sudden drop of reservoir water level combined with rainfall

为研究库水位骤降联合降雨情况下某黏土心墙坝的渗流特性以及稳定性规律,利用Geo-studio软件,对库水位骤降、不同强度降雨以及降雨发生在库水位骤降的不同时刻下的某黏土心墙坝的渗流特性以及上下游坝坡的稳定性规律进行了数值模拟。计算结果表明:(1)库水位骤降工况下孔压降低152%,上游坝坡安全系数先减小12.8%,后略有增大,下游坝坡则增大0.5%,库水位下降速率越大,孔压下降越快,上游坝坡安全系数下降越快,最小安全系数越小,下游坝坡安全系数上升越快;(2)降雨工况下孔压先平均增大2.1%后降低至初始水平,安全系数则先减小0.3%后增大至初始水平,降雨强度越大,孔压上升的幅度越大,最小安全系数越小;(3)降雨发生在库水位骤降不同时刻下,孔压呈现先减小后保持不变,在降雨时刻呈现突然上升的趋势,上游坝坡安全系数先减小后维持不变,下游坝坡安全系数先增大后保持不变,在降雨时刻突然下降,降雨发生在库水位下降结束时刻安全系数最小。

In order to study the seepage characteristics and stability law of a dam with clay core-wall under the condition of sudden drop of reservoir water level combined with rainfall,the numerical simulations are made on the seepage characteristics of the dam and the stability laws of its upstream slope and downstream slope during sudden drop of the reservoir water level,rainfall with various intensities and the rainfall occurred at the different moment of the sudden drop of the reservoir water level.The calculation result shows that(1)the pore pressure is decreased by 152%under the operation condition of the sudden drop of the reservoir water level,the safety factor of the upstream slope is firstly decreased by 12.8%and then slightly increased later,while the safety factor of the downstream slope is increased by 0.5%.The larger the rate of the drop of reservoir water level is,the faster the decrease of pore pressure is to be,the faster the drop of safety factor of the upstream slope is to be,the smaller the minimum safety factor is to be and the faster the rise of the safety factor of the downstream slope is to be as well;(2)under the condition of rainfall,the pore pressure is averagely increased 2.1%at first and then is decreased to the initial level,while the safety factor is decreased by 0.3%at first and then is increased to the initial level,moreover,the larger the rainfall intensity is,the larger the rising amplitude of pore pressure is to be and the smaller the minimum safety factor is to be as well;(3)if rainfall occurs the different moment of the sudden drop of the reservoir water level,pore pressure is decreased at first and then remains unchanged and exhibits a sudden rising trend at the moment of rainfall,while the safety factor of the upstream slope is decreased at first and then remains unchanged and the safety factor of the downstream slope is increased at first and then remains unchanged,which is suddenly decreased at the moment of rainfall.When rainfall occurs at the moment of the end of reservoir water level drop the safety factor is the smallest.