白鹤滩水电站初始地应力场研究分析

Research on initial stress field of Baihetan hydropower station

金沙江下游拟建的白鹤滩水电站上接乌东德梯级,下邻溪洛渡梯级,是继三峡和溪洛渡之后又一座千万千瓦级的水电站。白鹤滩水电站采用地下式厂房,其厂房的高度和跨度分别为78.5m和32m。为了保证地下洞室群围岩的稳定性,需要准确掌握初始地应力场的方向和大小。依据地质构造作用和现场实测方法分析发现,白鹤滩水电站左、右岸的初始地应力场,由于受到河流侵蚀和岸坡卸荷等因素影响,两岸厂区的地应力场方向在局部产生一定的偏转,从该地区的NWW方向变为NE方向,通过数值反演方法对计算区域的边界条件进行回归,与实测值比较确定回归边界条件的合理性和准确性。

A planned Baihetan hydropower station on the lower reaches of the Jinsha River, located between the hydropower stations of Wudongde and Xiluodu, is the third biggest hydropower station following the Three Gorges project and the Xiluodu power station. The station will have an installation capacity of 10 million kW. Baihetan hydropower station uses underground powerhouse, of which height and span respectively are 78.5 m and 32 m. To guarantee stability of wall rock of underground cavern, it is necessary to know the magnitude and direction of initial in-situ stress field exactly. Based on geological structure analysis and field testing, it is found that the directions of initial in-situ stress fields of both banks of Baihetan hydropower station, which are influenced by factors, such as fluvial erosion and slope unloading deflect from NWW to NE partly. Numerical inverse method is used to inverse boundary conditions of study area, it has rationality and veracity by comparing with measuring values.