锦屏一级水电站左岸坝肩高边坡长期稳定性数值分析

NUMERICAL ANALYSIS OF LONG-TERM STABILITY OF LEFT BANK ABUTMENT HIGH SLOPE AT JINPING I HYDROPOWER STATION

锦屏一级水电站左岸坝肩高边坡长期稳定性事关该水电站的正常安全运营。为充分掌握左岸岩石高边坡长期稳定性,建立了含f5,f8,f2,f42–9和煌斑岩脉X等软弱结构面的地质力学模型,并采用西原模型及有限差分数值计算方法,模拟正常蓄水位下左岸边坡岩体的长期力学行为。数值分析结果显示:左岸坝肩高边坡蠕变数值计算结果与现场监测数据总体位移变化趋势基本一致;经过一段时间后,边坡岩体蠕变位移变化基本趋于稳定,蠕变速率逐渐趋于恒定,西原模型可以反映锦屏一级水电站左岸边坡岩体的蠕变变形特性;在f5,f8,f2,f42–9和煌斑岩脉X出露区域以及开口线外危岩体边坡、1 960 m高程以上缆机平台边坡、1 885~1 960 m高程开挖边坡、"大块体"、PD44X平洞深部岩体等部位的蠕变位移变化比较明显;特别是拱肩槽1 730 m高程开挖平台与软弱结构面交汇部位,由于受到拱坝的拱端推力作用,蠕变变形更为明显,应重点关注,加强监测力度。

The long-term stability of left bank abutment high slope greatly affects the normal operation and safety of Jinping I hydropower station. In order to sufficiently understand the long-term stability of left bank abutment high slope,a geomechanical model containing weak structural planes of f5,f8,f2,f42–9 and lamprophyre veins X is established. The long-term creep behavior of slope rock mass is simulated under normal water level condition by using of Nishihara model and finite difference numerical calculation method. Results of numerical analysis show that the basic tendency of change for long-term creep numerical calculation results and field monitoring data of engineering are consistent. After a period of time,the specific creep deformation of slope rock mass gradually tended to be constant,and the creep rate went to a steady value. The Nishihara rheological model could reflect the rheological deformation characteristics of slope rock mass in Jinping I hydropower station. Creep deformation was obvious in many positions,such as the outcrop regions of f5,f8,f2,f42–9 and lamprophyre veins X,dangerous rock slope,cableway platform slope upper the elevation of 1 960 m,excavation slope in the elevation of 1 885~ 1 960 m,'bulk mass',deep rock mass of PD44X. The creep deformation of intersection parts between excavation platform of spandrel groove and weak structural plane in 1 730 m were more apparent under the thrust at push force of arch abutment condition,which needed to pay more attention and strengthen monitoring.