三峡库区某退水滞后型滑坡渗流及稳定性分析

Analysis on the Seepage of a Drawdown-Lag-Type Landside and Its Stability of the Three Gorges Reservoir Area

三峡库区自2003年蓄水以来,库区水岩作用引发了水库岸坡失稳等地质灾害,其中水库岸坡破坏出现在库水位上升期的占40%~49%,出现在水位消落期的约占30%,而有些大型滑坡会发生在库水位达到最大值后的快速消落期。本研究以三峡库区某退水滞后型滑坡为例,结合2016年1—6月三峡水库水位的实际运行情况并联合降雨,利用数值模拟的方法模拟其渗流场变化并进行稳定性计算。研究结果表明:库水位下降并叠加降雨的情况下,对滑坡的稳定性不利,当库水位下降速率达到1.0 m/d且叠加降雨时,滑坡的稳定性最差,此时为最不利工况;在5种工况条件下,滑坡的稳定性有所降低,但稳定性数值均大于1.05,说明滑坡仍处于基本稳定状态。

Since the storage of Three Gorges Reservoir in 2003,water-rock interaction has initiated a series of geological disasters of bank slope instability of the reservoir,of which,the destroyed bank slope occurred during the raising period of water level makes up 40%-49%,occurred during the falling period of water level occupies about 30%and some large-scale landslides will happen in the quick falling period when the reservoir water level reaches to the maximum value.The study simulated the variation of a seepage field and calculated its stability by using the method of numerical simulation,taking a drawdown-lag-type landslide of the reservoir area as an example and combining with the actual operation of the reservoir water level and rainfall in the period of January-June 2016.The outcomes show that a)under the conditions of water level falling plus rainfall,it is unfavorable to the stability of landslide.When the falling rate of water level reaches to 1.0 m/d plus rainfall,the stability value of landslide is the minimum which is the worst engineering condition and;b)among 5 engineering conditions,the stability of landslide is decreased somewhat,but the stability values are all greater than 1.05,showing that the landslide is still in the basically stable state.