杨房沟水电站河谷演化模拟及边坡稳定性分析

Analysis on Valley Evolvement and Slope Stability of Yangfanggou Hydropower Station

采用ITASCA公司的UDEC^(V4.0)数值模拟程序,建立杨房沟水电站坝址区典型剖面的二维离散元模型,模拟坝址区河谷发育的过程,基于模拟结果,分析坝址区边坡的应力及塑性区发育规律。结果表明,由于侵蚀切割作用导致边坡岩体的应力重分布,使其应力状态呈现为原岩应力区、应力松弛区、应力集中区及应力过渡区;塑性区水平发育深度在10~30 m之间,左岸较右岸略深,发育特征与实际卸荷带相符;在地应力场模拟结果的基础上,采用强度折减法计算河谷边坡总体安全稳定系数为1.89。

The 2D distinct element model of typical geological profile in dam site of Yangfanggou Hydropower Station is established by using UDECv4.0 to simulate valley evolution. Based on simulation results, the evolution laws of stress and plastic zone in slopes of dam site are analyzed. The results show that： （a） the stress field appears as four sub zones of original zone, relaxation zone, concentration zone and transition zone due to the stress re-distribution of rock mass caused by erosion cutting, and （b） the horizontal depth of plastic zone is about 10 - 30 m and the developing depth in left bank slope is larger than depth in right bank slope, which are consistent with actual geological conditions at dam site. On the basis of simulation results, the coefficient of slope stability is calculated as 1.89 when using the method of strength reduction.