洪石岩水电站厂房后边坡稳定性分析

洪石岩水电站是牛栏江水电规划的第六级电站,其厂房边坡地质条件复杂。厂房开挖边坡的下部有一条小断层通过,断层面以上边坡岩体破碎。通过调压井及引水道的开挖,可以确定边坡潜在滑面的形式。稳定分析采用边坡工程中常用的Bishop法和不平衡推力法。滑面力学参数通过反演算法确定,即根据边坡所处的发育阶段及相应的稳定程度,用开挖后的边坡进行反算。根据现场调查所得滑面粘聚力、岩石容重及规范规定的边坡安全系数,可以反算断层结构面的内摩擦角。通过计算,其结果低于规范规定值,因此,采用该结果进行边坡加固设计是偏安全的。

Analysis on stability of back side slope of powerhouse for Hongshiyan Hydropower Station

Hongshiyan Hydropower Station is the sixth step within the Hydroelectric Planning of Niulan River;of which the geological condition of the slope behind the powerhouse is very complicated.There is a fault through the bottom of the slope,and the rock mass above it is fragmentized.The shape of the potential slipping surface of the slope is determined through the excavation of both the surge tank and the water diversion tunnel.Bishop method and imbalance thrust force method are used in the stability analysis on the slope.The mechanical parameters of the slipping surface are determined through inversion algorithms,i.e.the parameters are back calculated based on the excavated slope.The inner friction angle of the slipping surface structure are also back-calculated in accordance with the cohesion of the slipping surface obtained from the site investigation,the density of rock and the slope safety coefficient stipulated in the relevant specifications.The result from the calculation is less than what stipulated in the relevant specifications,and then it is reliable to take the result for the design of the slope strengthening.