前坪水库溢洪道高边坡设计方案优化研究

前坪水库溢洪道高边坡的初步设计方案中,开挖边坡坡度为1∶0.5,采用5 m长锚杆Φ25 mm@2×2 m加固支护。通过系统优化研究,调整开挖边坡坡度为1∶0.4,采用10 m长锚杆Φ25 mm@3×3 m加固支护。采用GEO-SLOPE软件对不同工况下前坪水库溢洪道高边坡的稳定性进行了极限平衡分析,并采用FLAC 3D软件计算了不同工况下边坡的应力和变形分布规律。计算结果表明:优化设计方案中溢洪道高边坡开挖后在无水、正常水位及相应地震工况下的安全系数均大于1.3,满足规范要求。按优化设计方案开挖后,边坡在无水、遭遇洪水及地震3种工况下,开挖面上的最大主应力均出现拉应力,3种工况下的最大拉应力为0.24 MPa,小于安山玢岩的抗拉强度。优化设计方案与初步设计阶段的方案相比,可减少土石方开挖量约5万m3,具有显著的经济效益。

Optimization of Design Scheme for High Slope of Spillway in Qianping Reservoir

In the preliminary design of the spillway high slope of Qianping Reservoir,the slope of the excavated slope is 1:0.5 with 5 m long anchor rod,φ25 mm@2×2 m reinforced anchors.Through the system optimization study,the slope of the adjusted excavation slope is 1:0.4 with 10 m long anchor rod,φ25 mm@3×3 m reinforced anchors.The GEO-SLOPE software was used to analyze the stability of the high slope of the spillway of Qianping Reservoir under different working conditions,and the stress and deformation distribution rules of slope under different working conditions were calculated by FLAC 3D.The calculation results show that the safety factor of the high slope of the spillway in the optimized design scheme is greater than 1.3 after the excavation at the water free,normal water level and the corresponding seismic conditions,to meet the specification requirements.After the excavation according to the optimized design scheme,the maximum principal stress on the excavation surface appears tensile stress under the three conditions of water,flood and earthquakes,and the maximum tensile stress is 0.24 MPa under three conditions,which is less than that of the and esiticporphyrite.Compared with the preliminary design phase,the optimized design scheme can reduce the excavation quantity of earthwork about 50 000 m3,and has significant economic benefits.