小南海水电站左岸溢流坝抗滑稳定分析

Analysis of Stability against Sliding for Left Bank Overflow Dam of Xiaonanhai Hydropower Station

小南海水电站左岸溢流坝坝基内发育有层间剪切带、地层挠曲、顺河向的长大裂隙等,使其存在抗滑稳定问题。经分析该坝段的工程地质条件,确定坝基中可能出现的深层滑动破坏模式后,分别运用刚体极限平衡法和基于FLAC 3D的强度折减法计算坝基抗滑稳定安全系数,对比分析两种方法的计算成果。由强度折减法计算所得的安全系数均高于混凝土重力坝设计规范中规定的安全系数1.10,表明坝基的可能破坏模式不会发生,而刚体极限平衡法所得安全系数较强度折减法偏小,表明坝基的双斜滑动失稳模式可能发生,需要引起注意。但是对于不同的下游反向缓倾角裂隙倾角,两种方法所得安全系数的关系曲线变化趋势是一样的,倾角为40°时安全系数最小。

Because interlayer shear zone, formation deflection and large fracture along the river are developed in left bank overflow dam of Xiaonanhai hydropower station, so barn has stability against sliding. After analyzing engineering geological condition of the left bank spillway dam, and determining the possible failure mode of deep sliding, stability safety factor of dam has been calculated by using the rigid body limit equilibrium method and strength reduction method based on FLAC 3D, and calculation results of two methods have been analyzed. Stability safety factors of strength reduction method are higher than 1. l0 of design code of concrete gravity dam, which suggests that possible failure mode is not going to happen. And stability safety factor of the possibility of rigid body limit equilibrium method are smaller than that of strength reduction method, which shows that slide of double - taper wedge of dam may occur, so it requires attention. However, to different downstream reverse inclined fracture dip angle, the safety factors of the curves are the same, and the minimum safety factor is dip angle of 40°.