黄河上游哇让抽水蓄能电站下库进/出水口边坡稳定性研究

Study on Slope Stability of Inlet/Outlet of Lower Reservoir of Warang Pumped Storage Power Station in Upper Yellow River

高山峡谷地区水电工程中的边坡失稳问题十分常见,对工程的建设与水库运行安全有着重要影响.以黄河上游哇让抽水蓄能电站下库进/出水口边坡为研究对象,基于平硐编录、钻孔电视等方法对岩体结构面进行统计;通过钻孔波速测试,开展边坡岩体卸荷分带;据此,对边坡潜在破坏模式进行定性分析.通过UDEC软件,建立基于DFN离散裂隙网络的边坡离散元模型,考虑天然、暴雨和地震3种工况,分别对自然边坡、无支护开挖过程以及支护开挖过程进行数值模拟,揭示边坡潜在变形主控因素.结果显示,边坡的变形破坏主要受卸荷裂隙和顺坡向缓倾裂隙两组结构面控制,潜在变形模式为台阶状滑移-拉裂破坏;稳定性研究表明,自然边坡在3种工况下,抗滑稳定性均不满足规范要求.为保证进出水口安全,结合边坡变形模式和工程经验,提出了相应的开挖支护方案.研究表明,该支护方案有效可行,可有效提高边坡稳定性且使稳定系数满足规范要求.

Slope instability is very common in the process of building hydropower projects in alpine canyon areas,which has an important impact on engineering construction.In this paper,the slope of the inlet/outlet of the lower reservoir of the Warang pumped storage power station in the upper reach of the Yellow River is taken as the research object.Based on the methods of adit logging and borehole TV,the rock mass structural plane is counted:Through borehole wave velocity test,unloading zoning of slope rock mass is carried out.Accordingly,the potential failure mode of the slope is qualitatively analyzed.Through UDEC software,a discrete element model of slope based on DFN discrete fracture network is established.Considering three working conditions of natural,rainstorm and earthquake,the numerical simulation of natural slope,unsupported excavation process and supported excavation process are carried out respectively to reveal the main controlling factors of potential deformation of slope.The results show that the deformation and failure of the slope are mainly controlled by two groups of structural planes:unloading fissures and gently inclined fissures along the slope.The potential deformation mode is step-like slip-crack failure.The stability study shows that the anti-sliding stability of the natural slope does not meet the specification requirements under three working conditions.In order to ensure the safety of inlet and outlet,combined with slope deformation mode and engineering experience,the corresponding excavation support scheme is proposed.The research shows that the supporting scheme is effective and feasible,which can effectively improve the slope stability and make the stability coefficient meet the specification requirements under different working conditions.