三峡水库蓄水运行滑坡渗流稳定和防治设计研究

Research on seepage stability and prevention design of landslides during impoundment operation of the Three Gorges Reservoir,China

跟踪分析2008~2020年三峡工程175 m正常高程设计水位试验运行调度过程,建立正常工况下库水位多年平均升降典型曲线。以巫山塔坪滑坡为例,通过修正的一维非稳定渗流方程解析解,建立库水位多年平均升降与典型堆积层滑坡地下水浸润线的关系;由此,采用包含时间变量的不平衡推力法计算堆积层滑坡安全系数随库水位升降的动态曲线。并采用数值模拟验证解析分析的结果。考虑到库岸堆积层滑坡地下水与库水联通性良好,难以使用常规抗滑桩工程,本文还讨论采用中小口径抗滑桩群对水库滑坡进行防治的方法。值得指出,2020年8月,三峡库区遭遇自2003年建库以来的最大洪峰流量(百年一遇),达到75 000 m^(3)/s。本文对该水文年的滑坡稳定性进行了研究,可为特殊工况下库区滑坡稳定性分析和防治设计提供参考。

In this paper,the 175 m reservoir water level operation process of the Three Gorges Reservoir Project from 2008 to 2020 is analyzed,and a typical curve of the average annual reservoir water level fluctuation is obtained.Taking the Taping landslide in Wushan county as a case study,the relationship between the average reservoir water level fluctuation and the phreatic line in the typical accumulative landslide is established by the modified analytical solution of one-dimensional unsteady seepage equation. Furthermore,the unbalanced thrust method considering time variable is used to calculate the factor of safety of the accumulative landslide under reservoir water level fluctuation. Considering the good connection between reservoir water and groundwater in the reservoir landslide,it is difficult to adopt conventional anti-slide piles in prevention engineering,and hence,the small and medium calibre anti-slide pile group is proposed to be adopted in the prevention design of the reservoir landslide in this paper.It is worth noting that,in August 2020,the Three Gorges Reservoir area encountered the maximum peak discharge since the construction of the dam in 2003,reaching 75 000 m^(3)/s,therefore,the study on the landslide stability in the hydrological year can provide a reference for the stability analysis and prevention design of the reservoir landslides under special working conditions.