三峡库区水位变化对树坪滑坡变形影响机制研究

摘要

After impoundment of the Three Gorges reservoir,numerous landslides relevant to water have the signs of deformation.Deformation of most landslides rapidly increases,especially in the process of decline of reservoir water level.Shuping landslide,about 47 km from the dam site of Three Gorges,belongs to a kind of giant ancient accu-mulation body.Monitoring results for several years showed that Shuping landslide strongly deformed when reservoir water level dropped,significant losses will occur if the landslide loses stability.In light of the problem,we collect-ed monitoring data of Shuping landslide in recent years and analyzed its deformation mechanism in association with geological survey and exploration data.The results show that:1 )the fluctuation of underground water level of Shuping landslide is consistent with that of reservoir water level,but the variation of reservoir water level is relative-ly lagged;2)hydrodynamic pressure occurs in the condition of decline of reservoir water level,which is unfavor-able to landslide stability,at the same time,GPS data indicate intense deformation of the landslide with typical fea-tures of hydrodynamic pressure-type landslide;3)monitoring results measured by auto-recording displacement me-ter show that overall deformation is the main kind of deformations for Shuping landslide after impoundment with wa-ter level of 175 m,and it has deformation features of tractive landslide whose deformation in the bottom leads to slip in the top.%三峡水库蓄水后，众多涉水型滑坡均有变形迹象，尤其在库水位下降过程中，多数滑坡变形加剧。树坪滑坡属巨型古堆积体滑坡，距三峡大坝坝址约47 km，数年监测结果显示树坪滑坡在库水位下降过程中有强烈变形，若失稳将造成重大损失。为此，现场采集了树坪滑坡近几年监测数据，结合地质调查及勘探资料对其变形机制进行分析，结果表明：树坪滑坡地下水位与库水位涨落保持一致，库水位相对滞后，库水位下降时产生不利于滑坡体稳定性的动水压力，此时 GPS 数据表现出滑坡发生较强烈的变形，具有典型的动水压力型滑坡特征；自动位移计监测结果表明：树坪滑坡在库水位蓄水至175 m 水位后主要发生整体变形，由下部变形牵引上部滑动，具有牵引式滑坡的变形特征。