黄河龙羊峡水电站近坝库岸龙西滑坡体高水位运行期变形特征分析

Deformation characteristics of Longxi landslide at reservoir bank near Longyangxia dam duringhigh water level operation

滑坡体失稳的主要前兆是后缘拉裂缝的不断扩张和滑坡体是否持续变形。黄河龙羊峡水电站近坝库岸龙西滑坡体在2005年之后的高水位运行期间,滑坡体水准及硐内水准各测点观测值均有不同程度的抬升趋势,滑坡体后缘裂缝也有扩张迹象。为了掌握龙西滑坡体的变形规律,准确判断其失稳动态,对此滑坡体地质条件、变形破坏特征和监测资料进行了综合分析,认为:在高水位运行期龙西滑坡体的变形速率基本平稳,没有加快变形,滑坡体后缘大部分裂缝也无明显增宽和延展。目前,龙西滑坡体整体呈稳定状态,除临水岸坡产生小规模崩塌、岸坡后退,形成新的水下堆积坡,滑坡体无明显的大体积滑移迹象。水准观测各测点的抬升对龙西滑坡体稳定的影响尚不明显。

The main precursors of the landslide destabilization are continuous expansion of the tensioncrack at rear edge and continuous deformation of the landslide. During high water level operation ofLongyangxia hydropower station since 2005, the observed values of measuring points of the landslidebody leveling and the cave leveling have risen to different degree and the crack at rear edge of the land-slide body has also expanded.In order to grasp the deformation law of Longxi landslide and determine the stabilization statecorrectly, the authors have comprehensively analyzed the geological conditions, deformation and failurecharacteristics of landslide and monitoring data. And the conclusion has been obtained that the deforma-tion rate of Longxi landslide is basically stable, and there is no obvious widening and extension in mostof tension cracks on the trailing edge. By now, Longxi landslide is in stable state. Except some small-scale collapse near the reservoir bank, bank slope recession and the formation of new underwater accu-mulation, there is no sign of large volume slipping of the landslide. How the raise of observed levelingvalues influence the stability of Longxi landslide is not clear yet.