库水位变动条件下谭家河滑坡变形阈值分析

Deformation Threshold Analysis of Tanjiahe Landslide Under the Condition of Reservoir Water Level Change

水库型滑坡主要受水库蓄水、水位升降以及降雨等综合因素影响,稳定性差、变形机理复杂,同时其规模一般较大、危害性强;以三峡库首区域典型代表性水库滑坡-秭归谭家河滑坡为例,对丰富的专业监测数据进行了深入细致的分析,研究结果表明:滑坡主要受到库水位变动的影响,当库水位达到172 m时,滑坡开始产生较大的变形;由于长期库水位变动的影响,滑坡在高库水位和库水位下降时,位移速率较大,监测曲线形成阶跃,滑坡同时受到浮托减重效应和动水压力效应的影响.在库水位下降期,7d累积降雨量大于70 mm,以及在145 m低水位运行期,7 d累积降雨量超过170 mm,会对滑坡的变形产生明显的影响.

Reservoir landslide is mainly affected by comprehensive factors including reservoir pondage,the change of water level,and rainfall.It is featured by poor stability,complex deformation mechanism,large damage area and severe harm.In this paper,the typical reservoir landslide in the Three Gorges Reservoir area,the Tanjiahe landslide in Zigui County,is studied.The professional monitoring data are thoroughly analyzed.The research results show that the landslide is mainly affected by the change of the reservoir water level.The landslide begins to produce a large deformation when the water level of the reservoir reaches 172m.Under the long-term influence of the change of reservoir water level,landslide presents larger displacement rate,and step changes appears in the monitoring curve when the reservoir water level is high and the reservoir water level is falling.The landslide is also affected by the buoyancy-reducing and water pressure effects at the same time.During periods of decreasing water level,when the 7-day cumulative rainfall is greater than 70mm,or during the operation period at low water level of 145m,when the 7-day cumulative rainfall exceeds 170mm,there will be a significant impact on the deformation of the landslide.