Study on Slope Stability of Inlet / Outlet of Lower Reservoir of Warang Pumped Storage Power Station in Upper Yellow River
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摘要: 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.Abstract: 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.
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图 1 哇让抽水蓄能电站位置及进/出水口边坡地貌
a.哇让抽蓄电站地理位置图；b.进出水口边坡
Fig. 1. Location and slope landform of inlet/outlet of lower reservoir of Warang pumped storage power station
图 5 工程区结构面测绘结果
a.节理极点等密图；b.结构面与坡面的产状关系
Fig. 5. Mapping results of the structural plane in the engineering area
图 9 自然边坡在强度折减过程中监测点位移变化曲线
Fig. 9. Displacement curves of monitoring points during strength reduction of natural slope
图 10 自然边坡在不同强度折减系数条件下的位移云图
Fig. 10. Displacement nephogram of natural slope under different strength reduction factors a. Ks = 1.02; b. Ks = 1.18
图 11 自然边坡最终破坏模式：台阶状滑移-拉裂破坏
Fig. 11. The final failure mode of natural slope-step slip-crack failure
图 12 暴雨工况下监测点位移与强度折减系数的变化曲线
Fig. 12. Curves of displacement and strength reduction factor of natural slope monitoring points under rainstorm
图 13 地震工况下监测点位移与强度折减系数的关系曲线
Fig. 13. Displacement and strength reduction of natural slope monitoring points under earthquake
图 15 无支护开挖过程监测点变形变化历程
Fig. 15. Deformation change process of monitoring points during unsupported excavation
图 16 无支护开挖条件下边坡监测点位移随强度折减系数的变化曲线
Fig. 16. Change curve of displacement and strength reduction coefficient of slope monitoring point under unsupported excavation condition
图 18 开挖并支护完成后边坡的位移云图
Fig. 18. Variation of displacement nephogram of slope under the condition of step excavation and support
图 19 天然工况下已支护边坡监测点位移随强度折减系数的变化曲线
Fig. 19. Displacement of monitoring points of supported slope with reduction coefficient under natural conditions
图 20 天然工况下支护结构内力分布随折减系数的变化
Fig. 20. Under natural conditions, the changes of the internal force with the strength reduction factor
a. Ks = 1.20; b. Ks = 1.25; c. Ks = 1.30; d. Ks = 1.35; e. Ks = 1.37; f. Ks = 1.39
图 21 天然工况不同强度折减系数下的结构单元破坏情况
Fig. 21. Damage of structural units under different strength reduction factors under natural conditions a. Ks = 1.37; b. Ks = 1.39
图 22 暴雨工况下已支护边坡监测点位移与强度折减系数的变化曲线
Fig. 22. Change curve of displacement and strength reduction coefficient of monitoring points of supported slope under rainstorm condition
图 23 地震工况下已支护边坡监测点位移与强度折减系数的变化曲线
Fig. 23. Variation curves of displacement and strength reduction coefficient of monitoring points of supported slope under seismic condition
图 24 地震工况下不同折减系数下的结构单元破坏情况
a. 地震且Ks = 1.05；b. 地震且Ks = 1.18；c. 地震且Ks = 1.19；d.地震且Ks=1.20
Fig. 24. Failure of structural elements under different reduction factors in earthquake
表 1 结构面参数取值
Table 1. Parameter values of structural plane
区域 组别 法向刚度
(GPa/m)剪切刚度
(GPa/m)粘聚力
(MPa)抗拉强度
(MPa)内摩擦角
(°)强卸荷带 J1 20 20 0.48 0.24 25.7 J2 16 16 0.31 0.15 16.8 J3 10 10 0.24 0.12 16.8 弱卸荷带 J1 25 25 1 0.5 30 J2 20 20 0.38 0.19 21 J3 16 16 0.31 0.15 16.8 F5断层 / 10 10 0.1 0.05 16.8 新鲜岩体 / 30 30 2 1 35 
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表 2 岩石参数取值
Table 2. Rock parameter values
区域 密度
(kg/m3)体积模量
(GPa)剪切模量
(GPa)粘聚力
(MPa)抗拉强度
(MPa)内摩擦角
(°)强卸荷带 2 710 6.67 4.0 6.0 0.55 28 弱卸荷带 2 710 25.30 16.0 25.0 2.50 30 F5断层 2 710 6.67 4.0 6.0 0.55 28 新鲜岩体 2 720 25.30 17.4 29.0 2.90 35
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表 3 梁单元强度取值
Table 3. Strength values of beam element
梁单元参数 取值 密度（kg/m3） 2 500 泊松比 0.15 抗压屈强度（MPa） 4 抗拉屈强度（MPa） 2 杨氏模量（GPa） 20 厚度（m） 0.2 界面摩擦角（°） 45 界面粘结强度（MPa） 1 界面抗拉强度（MPa） 0.1 界面法向刚度（GPa） 20 界面剪切刚度（GPa） 10
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表 4 锚杆单元强度取值
Table 4. Strength values of bolt element
锚杆参数 系统锚 锚筋桩 预应力锚索 锁口锚杆 型号、直径（mm） C25/C28 3C28 10φj15.24 C28 密度（kg/m3） 7 500 7 500 7 500 7 500 抗压屈强度（GPa） 10 10 10 10 极限抗拉强度（kN） 88/110 166 650 220 杨氏模量（GPa） 49 25 25 98 粘结刚度（GPa） 4.8/5.2 2.9 3.6 10 粘结强度（kN/m） 39/44 38 33 88 间距（m） 2.0 4.0 4.0 1.0 预应力（吨） / / 37.5 /
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