库水联合降雨条件下白水河滑坡的稳定性研究

胡泽铭 肖长波 谭超

摘要：库水位下降和降雨对库岸滑坡的稳定性具有重要影响，但现有研究对这两种因素的考虑过于理想化。本文在综合考虑减灾、航运、发电等的基础上，针对库水下降阶段提出了新的库水下降模型;结合近五十年的降雨数据，考虑到实际降雨量和降雨加载时间等因素提出了降雨模型。最后以白水河滑坡为例，分析了滑坡在降雨和不同库水下降速率条件下的稳定性。结果表明，白水河滑坡主要由库水下降影响，采用末期加速下降模型时，能有效减少库水位持续下降对滑坡的影响，其稳定系数较正常工况减小约0.7%～1.2%。本文所提出的库水位下降模型对实际库水调度具有重要参考意义。

关键词：库水位下降;降雨;滑坡;稳定性;三峡库区

Abstract：Reservoir drawdown and rainfall have important influence on bank landslides，but existing research on these two factors is too idealistic. A new reservoir drawdown model was proposed for the rapid drawdown stage based on the consideration of reduction，navigation and power generation. A rainfall model was proposed considering actural rainfall and rainfall time based on fifty years of daily rainfall data. At last，taking Baishuihe landslide as an example，the landslide stability was analyzed under the combined influenced of rainfall and reservoir drawdown. Results show that the Baishuihe landslide is mainly influenced by reservoir drawdown. The terminal reservoir drawdown model can reduce the effect of continuous decline of reservoir on landslide and the stability decreases about 0.7% ～ 1.2% compared with normal scenario. The reservoir drawdown model proposed in this paper is of significance to the reservoir operation in the Three Gorges Reservoir.

Key words：reservoir drawdown;rainfall;landslide;stability;Three Gorges Reservoir

1 前言

库水位变动和降雨是诱发库岸滑坡的重要因素[1-3]。三峡库区蓄水之初，库水的下降速率被严格限制为小于0.6 m/d。在库水平稳运行8年后，库岸基本适应了新的周期性水文地质条件。前期设定的0.6 m/d的最大日降幅，限制了三峡大坝效益的发挥，有必要研究增加库水位下降速率对滑坡稳定性的影响。

近些年，关于降雨和库水联合作用下滑坡稳定性问题有了比较广泛的研究。王力[5]、张桂荣[6]、王鹏[7]等研究了库水以恒定速率从175m降至145m时滑坡的稳定性，并研究下降速率对滑坡稳定性的影响;肖志勇等[8]分析了库水从175 m间歇性下降至145 m时滑坡的稳定性。以上研究忽略了库水位的实际调度及降雨的分布，两种重要的影响因素被过分简化。……