四川深溪沟水电站苏姑坪危岩体变形特征及其机理研究

苏姑坪危岩体位于四川大渡河深溪沟水电站库区,破坏失稳后很可能堵塞大渡河,给该水电站、成昆铁路以及上游瀑布沟水电站的安全构成威胁.本文在现场调查测绘资料的基础上,利用岩土工程地质力学分析原理,对该危岩体的变形特征、变形机制及其破坏模式进行了分析,建立了危岩体流变滑移力学模型并以此预测其变形破裂失稳时间.研究结果表明该危岩体变形破裂模式为卸荷-拉裂-蠕滑型,即岸坡岩体随着大渡河下切卸荷变形,在后缘形成近垂直拉裂缝,同时在自重和外部偶然荷载作用下沿缓倾坡外的层面发生剪切蠕滑变形.最后基于流变模型并根据前期蠕滑速率推测出失稳时间.

THE CHARACTERISTICS AND DEFORMATION MECHANISM OF SUGUPING CRAG IN SHENXIGOU IN SICHUAN PROVINCE

uguping crag is located in Shenxigou Hydropower Station reservoir area of the Dadu river in Sichuan province. The crag, which is destroyed and lose stability, will jam the Dadu river, arousing great hidden trouble to the Cheng-Kun railway and upriver Zipinpu hydropower station as well as Shenxigou. Through studying the characteristics and the mode of deformation and destruction, with utilizing geologic mechanics analysis principle of rock-soil engeering, a rheological mechanics model has been set up based on the investigation and mapping datum on the site, which can be used to predict instability time for the crag body. It is illuminated that the mode of deformation and destruction is the unloading- ripping going with creeping. It is demonstrated that the deformation is initiated by unloading along with down--cutting of the Dadu river, leading to amostly vertically ripping of the upper bank rock layer and sheering of the ratherish inclining--outside lay because of the gravity and exterior casual load. Finaly, the instability time is calculated by the mechanics model and the prophase creeping velocity.