锦屏二级水电站引水隧洞减压孔布置方案优化

Layout optimization of drainage holes in the hydraulic tunnels of Jinping Ⅱ Hydropower Station

以锦屏二级水电站引水隧洞为研究对象,以衬砌最大压应力为目标,对减压孔布置方案进行优化分析。考虑减压孔孔径、间距和入岩深度的影响,通过正交设计数值试验,确定这几项因素对衬砌外缘水压力的影响程度从大到小排列顺序为:减压孔入岩深度、孔径、间距,且随着孔隙水压力的增大,不同布置方案对泄压效果的影响逐渐减弱,衬砌安装1周后,其影响范围达到0.3 MPa。因此,为降低衬砌外缘水压力,保证衬砌的安全性,宜优先考虑增大减压孔的入岩深度。通过极差分析,得到各因素对衬砌结构安全性的影响,并确定减压孔最优布置方案为间距2.86 m、孔径0.2m、入岩深度0.2 m。

Along with the exploitation of underground space approaching to the deep constantly,the high external water pressure is posing a big threat to the safety of lining structure. Drainage holes are often used to release the pressure in the engineering practice. An optimization analysis of the drainage hole layout based on the stress target of lining was carried out in this study. The effect of the drain hole diameter,spacing and entry depth in rock on the water pressure was studied by orthogonal numerical tests. The results showed that influencing factors can be ordered as entry depth,diameter and spacing,from a high influence to a low influence,and with the pore pressure increasing,the influence of different layout decreased. A week after lining installation,the influence of different layouts reached 0. 3 MPa. Therefore,to reduce the water pressure on lining and ensure the safety of the lining,it s preferred to increase the entry depth. Through the range analysis,influences of factors on the lining security were obtained,and the optimal drainage holes arrangement scheme was determined as 2. 86 m in spacing,0. 2 m in diameter and 0. 2 m in entry depth,which means a great significance for the drainage hole design of hydraulic tunnels.