西南某巨型水电站坝区推覆断层研究

马家河坝断层发育于金沙江某巨型水电站库区,距坝址最近仅3km,且沿江两岸出露,主断面不同部分和次级断层结构样式和变形特征复杂。所以对断层的认识一直是大坝稳定性评价的重点也是争论的焦点。通过大比例尺野外填图、开挖平硐和室内构造解析获得了大量新资料,认为该断层是一个发育在地台内部的小型推覆构造。首次厘定了断层几何学和运动学特征和影响范围,分析了断层的动力学机制。这对大坝的施工和蓄水后的安全运行有重大意义。

A THRUST FAULT IN A HYDROPOWER PLANT RESERVOIR REGION IN THE SOUTHWEST CHINA

A fault lies across in a hydropower reservoir region only 3 km upstream of Majiahe dam on the Jinsha River Its structure patterns and deformation features vary greatly between different classes of fracture surfaces and even different parts of the primary fracture surfaces.Therefore,characterization of the fault is the key to stability assessment of the dam as well,which has been a hot topic for debating.Based on new data collected by large-scale geological mapping,surveying adits and structure analysis,the authors conclude that that fault is a small thrust in the interior area of a plateform.It is the first time that the geometry and kinematics features as well as influence region are determined.The dynamics of the fault formation is also analyzed.The research results provide information needed for construction and safe operation of the dam.