南水北调中线工程山门河隧洞支护及进洞设计

Supporting the Anchor Structure Design of Shanmen River Tunnel of Middle Route of South to North Water Transfer Project

山门河隧洞是南水北调中线工程中断面最大的无压引水隧洞,跨度大、覆盖层较薄、隧洞围岩条件较差。确定洞口支护方式时,经过结构计算,比较了喷锚支护、预应力锚固、地下连续墙等多种支护方案,最终确定采用钢筋混凝土地下连续墙方案。进洞设计借鉴了城市地铁施工中浅埋暗挖的方法,采用超前支护和开挖衬砌方案,临时衬砌结构采用格栅钢架喷厚30 cm的C25混凝土,先对洞顶进行预加固,再开挖洞身。

Shanmen River tunnel is the largest free flow tunnel in the tunnel section of Middle Route of South to North Water Transfer Project.It is a long-span,low covered,and poor conditions surrounding rock construction.After comparison of spray-anchor program,pre-stressed anchor program,underground diaphragm wall and other program,the underground diaphragm wall is used to finalize the hole support method.Learned from the metro construction in Shallow method,advance support excavation lining method is used.First,use temporary lining by steel grille sprayed 30 cm thick of C25 concrete to reinforce the roof,then dig the tunnel.