摘要:
针对库水位变化条件下滑坡的稳定性定量评价复杂问题,考虑降雨和库水位变化对地下水渗流场变化规律的影响机制,采用饱和-非饱和渗流的基本理论,运用渗流模拟有限元法,对重庆市武隆区羊角滩滑坡在6种不同工况下的库区滑坡的稳定性开展了模拟研究。结果表明: ①降雨工况下,降雨对地下水渗流场都有影响,滑坡中部位置受地下水位影响最大,前后部影响小,降雨条件下,滑坡稳定性随着降雨历时的增加而变小,到达一定阶段后,滑坡已经滑动,滑坡稳定性系数不再变化; ②库水位工况下,主要影响滑坡前缘,地下水位是随库水位变化而迅速变化的,随着库水位的上涨,滑坡稳定性系数呈现先减小后增大的趋势; ③地下水位的骤升对浮托作用影响有限,对压坡作用影响较大,同时降低了渗流力的影响,对滑坡稳定起到了积极作用,地下水位的骤降增大了渗流力,减弱了前缘库水位的压坡作用,滑坡失稳的可能性最大。可为库区该类滑坡的稳定性现状及发展趋势预判提供科学依据。
Abstract:
Aiming at the complex problem of quantitative evaluation of the landslide stability under the condition of reservoir water level change, the authors in this paper considered the influence mechanism of rainfall and reservoir water level changes on groundwater seepage field, and adopted the basic theory of saturated-unsaturated seepage and seepage simulation finite element method to simulate the Yangjiaotan landside stability in the reservoir area under 6 different conditions. The results show that: ① Rainfall has an impact on the groundwater seepage field, with the greatest impact in the middle of the groundwater level and little impact on the front and back. Under rainfall conditions, the stability of the landslide decreases with the increase in rainfall duration. The landslide began to slip after reaching a certain stage, and the landslide stability coefficient keep unchanged. ② Under the condition of the reservoir water level, the front edge of the landslide was mainly affected, and groundwater level changes rapidly with the change of the reservoir water level. The landslide stability coefficient shows a trend of first decreasing and then increasing with the rising reservoir water level. ③ The sudden rise of the groundwater level has limited impact on the floating effect, but it has a greater impact on counter poising. Besides, it also reduces the impact of the seepage force, which has a positive effect on the stability of the landslide. The sudden drop of the groundwater level increases the seepage force, weakening the effect of leading-edge reservoir water level on counter posing, so the possibility of landslide instability is greatest. The research results can provide a scientific basis for the prediction of the current stability and development trend of such landslides in the reservoir area.
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