某大型水电站左岸高边坡开挖数值模拟及支护建议

Numerical simulation and supporting measure of high slope excavation on left abutment of a large hydropower station

应用3D-σ软件对西南某大型水电站左岸边坡开挖过程进行三维数值模拟,模拟结果表明:开挖坡面产生不同程度的张拉应力区域;缆机平台和拱肩槽槽坡底部产生一些竖直方向的回弹变形和水平向坡外的变形;5~#梁山脊在拱肩槽开挖后将产生进一步的卸荷松弛,表层岩体稳定性将可能恶化,f42-9断层以上的大块岩体将是一个潜在的威胁;根据以上分析对开挖边坡制定了分层开挖、分层加固的方案,支护方案采用预应力锚索及排水系统的组合形式进行加固,支护后的稳定性计算表明,采用的支护措施是有效的,达到了工程设计的要求。

A 3D numerical simulation of high slope excavation in left abutment of a large hydropower station is carried out with a program 3D-σ.The result of analysis shows that the tensile stress zone exists at top of slope surface after excavation;the rock mass deformation in the horizontal direction and vertical direction appears at the bottom of spandrel groove and the cable-crane platform; excavation of spandrel groove leads to unloading relaxation and deterioration of surface rock mass in the mountain No.5;and the large block above the fault f42-9 will be a potential threat;all the above will be the focal point of slope support at excavating step by step.According to analysis above,supporting measures after excavation are carried out including combination supporting measures of prestressed cable and drain to cut the water.The result shows that the supporting measure is effective,which meets the needs of project design.