清江中游隔河岩库区偏山滑坡形成机制及稳定性分析

Formation Mechanism and Stability Analysis of the Pianshan Landslide in Geheyan Reservoir Area of the Middle Reaches of the Qingjiang River

偏山滑坡位于清江中游隔河岩库区,距隔河岩大坝54 km,是该库区的大型滑坡之一,其稳定性直接关系到50多户200多人的生命安全及隔河岩水库的正常运行。通过野外调查,采用工程地质测绘、钻探、物探、槽探等工程勘查手段,分析该滑坡的形成机制,查明除地形地貌、地层岩性、物质结构外,滑坡稳定性主要受暴雨、水库水位涨落等外动力因素的影响;从深部位移及地表位移、地表裂缝的监测结果分析,滑坡局部产生变形及位移,正处于蠕变阶段;通过滑坡稳定性计算,结合滑坡形成机制及影响因素分析,滑坡整体稳定性较好,但滑坡在暴雨加库水位骤降条件下,稳定系数有所降低,局部存在滑塌的可能。

Pianshan landslide, one of the large-scale landslides in Geheyan reservoir, occurs 54 km far away from Geheyan dam in the middle reach of the Qingjiang River. Since the stability of Pianshan landslide maybe directly threaten the safety of local more than 200 lives and normal operation of the Geheyan reservoir, it is of significance to carry out the study on the formation mechanism of landslide by the means of field investigation tecbiniques such as engineering geological mapping, drilling, geophysical, trench exploration and so on. The result shows the external driving factor is the mainly influencing factors on the landslide stability,such a as rainstorm and the water level fluctuation of the reservoir and topography, lithology, physical structures are the secondary factors. Monitoring results from deep displacement, surface displacement and surface cracks show the landslide is now in the creep stage and the deformation formed in partial section. Stability calculation of the landslide combined with the formation mechanism and influence factors show that the landslide is in the state of the integral stability, but the stability coefficient will be decreased and even slumping occur in local place under the conditions of rainstorm and sudden drawdown of reservoir water level.