
Shape Optimization Analysis at the Entrance of Discharge Structure on Right Bank of Lawa Hydropower Station
Dong LIU, Qing-xiang WANG, Wei WEI, Shen-yuan DENG
Shape Optimization Analysis at the Entrance of Discharge Structure on Right Bank of Lawa Hydropower Station
The geological conditions at the entrance of the discharge structure on the right bank of Lawa Hydropower Station are complicated. The maximum height of the excavated slope is about 220 m. After excavation, the slope foot has a high level of compressive stress and the stress concentration effect is obvious, which threatens the construction and operating safety of the discharge structure. The deformation, plastic zone and stress variation of slope during excavation, especially the influence of stress concentration at slope foot on slope stability, are analyzed by establishing the numerical models of slopes at different parts. The results show that the maximum compressive stress at the foot of EL2 654 m platform slope at the entrance of spillway tunnel is 18 MPa, which is 2.1 times higher than that at the main compressive stress before excavation. In order to ensure the stability of the rock mass at the foot of the slope, this paper studies the deformation and stress of the slope less than 2 709 m at different excavation slope ratios (vertical slope, 1∶0.3 and 1∶0.5). The results show that the excavation volume and the deformation of the slope are both small and the stress concentration at the foot of the slope obviously decreases when excavation slope ratio adopts 1∶0.3.
steep slope / numerical calculation / stress concentration / shape optimization / Lawa Hydropower Station {{custom_keyword}} /
Fig.2 The plane location and 3D effect drawing of the discharge structure图2 泄水建筑物平面位置及三维效果图 |
Tab.1 Mechanical parameters of rock mass and discontinuities表1 岩体和结构面力学参数 |
材料分类 | 变形模量E/GPa | 泊松比μ | 黏聚力c′/kPa | 摩擦系数f |
---|---|---|---|---|
III1类岩体 | 11.500 | 0.250 | 1 100 | 1.07 |
III2类岩体 | 6.500 | 0.300 | 975 | 0.90 |
IV1类岩体 | 3.000 | 0.350 | 650 | 0.75 |
IV2类岩体 | 2.000 | 0.350 | 450 | 0.63 |
V1类岩体 | 0.375 | 0.350 | 250 | 0.47 |
F331、F318、F109等 | 0.375 | 0.350 | 30 | 0.31 |
F271、F272、F126 、F121深卸荷裂隙 | 0.375 | 0.350 | 250 | 0.47 |
Fig.4 Nephogram and vector images of slope deformation of section 16-16 after excavation图4 剖面16-16开挖完成后边坡变形云图及矢量图 |
Fig.5 Nephogram and vector images of slope deformation of section 6-6 after excavation图5 剖面6-6开挖完成后边坡变形云图及矢量图 |
Fig.8 Stress distribution of slope foot at different parts of cat walk before and after excavation of section 16-16图8 进水渠16-16剖面边坡开挖前、后不同马道部位坡脚应力水平 |
Fig.9 Stress distribution of slope foot at different parts of cat walk before and after excavation of section 6-6图9 溢洪洞进口6-6剖面边坡开挖前、后不同马道部位坡脚应力水平 |
Tab.2 Displacement at typical sites in 6-6 section under different slope types表2 不同坡型条件下6-6剖面典型测点变形量 |
2 709 m以下开挖方案 | 2 800 m坡表 | 2 770 m坡表 | 2 740 m坡表 | 2 710 m坡表 | ||||
---|---|---|---|---|---|---|---|---|
水平位移/mm | 总位移/mm | 水平位移/mm | 总位移/mm | 水平位移/mm | 总位移/mm | 水平位移/mm | 总位移/mm | |
方案1(直立边坡) | -86.6 | -113.1 | -96.8 | -116.9 | -93.5 | -97.9 | -25.3 | -25.5 |
方案2(坡比1∶0.3) | -94.3 | -126.8 | -84.4 | -109.7 | -36.1 | -37.9 | -17.3 | -18.5 |
方案3(坡比1∶0.5) | -90.2 | -105.7 | -53.9 | -72.8 | -26.6 | -27.7 | -7.1 | -15.6 |
Fig.14 Distribution nephogram of principal compressive stress of slope图14 边坡主压应力分布云图 |
Tab.3 Principal compressive stress before and after excavation at typical sites in 6-6 section表3 6-6剖面典型测点开挖前后主压应力 |
2 709 m以下开挖方案 | 2 709 m坝顶公路 | 2 668 m坡脚 | ||||
---|---|---|---|---|---|---|
开挖前/MPa | 开挖后/MPa | 应力比 | 开挖前/MPa | 开挖后/MPa | 应力比 | |
方案1(直立边坡) | 6.5 | 7 | 1.1 | 8.2 | 17.5 | 2.1 |
方案2(坡比1∶0.3) | 7.1 | 10.2 | 1.4 | 8.2 | 13.5 | 1.6 |
方案3(坡比1∶0.5) | 7.3 | 12 | 1.6 | 8.2 | 11.6 | 1.4 |
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