三峡库区谭家湾滑坡降雨阈值研究

Rainfall threshold Value Induing the Tianjiawan Landslide in Three Gorges Reservoir Area

秭归县谭家湾滑坡是三峡库区典型的大型堆积层滑坡,近年来受降雨影响而变形明显,严重威胁人民的生命财产安全。在滑坡区域地质环境和累积位移曲线的基础上,分析了滑坡变形和降雨量的关系。研究表明:降雨为谭家湾滑坡变形最主要的诱发因素,滑坡累积位移曲线在持续性降雨和强降雨条件下呈“阶跃”特征,且阶跃变形发生明显的滞后现象;谭家湾滑坡“阶跃”加速的位移速率阈值为17 mm·d^(-1);前期降雨+当次降雨模式下谭家湾滑坡的前期降雨、当次降雨阈值分别为10、13 mm;持续降雨结束后,监测点位移速率恢复至正常要经过5~8 d;每一次降雨对滑坡变形的影响时间为8 d。

The Tanjiawan landslide in Zigui County is a typical large-scale landslide within colluvial in the Three Gorges Reser-voir area.In recent years,it has undergone a significant deformation due to the rainfall,posing a serious threat to people's lives and property.Based on the geological environment of the landslide area and the cumulative displacement curve,an analysis was conducted on the relationship between the landslide deformation and the rainfall.The study shows that the rainfall is the main triggering factor for the deformation of the Tanjiawan landslide.The cumulative displacement curve exhibits a"stepped"characteristic under the continuous rainfall and heavy rainfall conditions,with a noticeable lag in the occurrence of stepped de-formation.The threshold displacement rate for the accelerated"stepped"movement of the Tanjiawan landslide is 17 mm/day.The threshold value for antecedent rainfall and the current rainfall in the antecedent rainfall+the current rainfall model of the Tanjiawan landslide are 10 mm and 13 mm,respectively.After the end of the continuous rainfall,it takes 5~8 days for the displacement rate of monitoring points to return to normal.The impact of a single rainfall event on the landslide deformation lasts for8days.