大渡河瀑布沟水库红岩子滑坡变形特征与机理分析

Deformation characteristics and reactivation mechanism of Hongyanzi landslide in Pubugou reservoir area of the Dadu River

库水涨落常诱发库岸滑坡变形破坏。为了研究库岸滑坡的变形特征及变形机理,以大渡河瀑布沟水电站红岩子滑坡为对象,通过详细的地表宏观变形调查和对监测数据的深入分析,结合GeoStudio数值模拟,深入研究了该滑坡的变形特征、渗流场、稳定性及库水对滑坡的作用机理。结果表明:红岩子滑坡地表宏观变形显著,累计位移曲线呈“阶跃”式特征,库水下降是滑坡变形的主要诱发因素;库水位由850 m高水位集中下降至830 m以下时,位移阶跃启动,“阶跃”段的累计变形量占全年总变形量的90%以上,当库水位下降速率大于0.5 m/d时,滑坡加速变形;滑坡变形模式为蠕滑-拉裂,库水升降导致滑体内部渗透力的变化,对滑坡稳定性影响很大,引发滑坡“阶跃”变形。

Reservoir water fluctuation can often trigger deformation and failure of reservoir bank landslides.This study focuses on the Hongyanzi landslide in the Pubugou hydropower Station of the Dadu River to investigate the deformation characteristics and deformation mechanisms of the reservoir bank landslides.Through detailed surface macro deformation surveys,monitoring data analysis,and GeoStudio numerical simulation,the deformation characteristics,seepage field,stability and the influence of reservoir water on landslide were studied in depth.The research revealed significant macro deformation of the Hongyanzi landslide surface,with a cumulative displacement curve exhibiting a“step-like”characteristic.The primary inducing factor of landslide deformation was found to be the decrease in the reservoir water level.When the reservoir water level dropped from 850 m to below 830 m,the displacement step was triggered,and the cumulative deformation of the“step”segment accounted for over 90%of the total annual deformation.Accelerated deformation of the landslide occurred when the rate of the reservoir water level decline was greater than 0.5 m/d.The landslide deformation mode was identified as creep slip-tensile cracking,with the rise and fall of the reservoir water level significantly impacting the internal permeability of the sliding body and causing a large impact on the landslide’s stability,leading to the“step-like”deformation of the landslide.