引洮供水隧洞工程出口段开挖及支护技术

Excavation and Support Technique in Outlet Section of Tunnel in Tao River Delivery Project

引洮供水一期工程总干渠9号隧洞全长18.275km,断面形式为圆形,直径4.96km,其出口段长760m,围岩属极软岩;出口加强段长50m,为土洞。文中叙述了该两洞段的开挖、支护方法,包括:上下导洞的开挖,钻孔的布设,钢拱架和锚杆的安装,混凝土的喷射。

The total length of NO.9 tunnel in general main canal of Tao River Delivery Project（first stage）is 18.275 km.The tunnel＇s cross section shape is circular.Its diameter is 4.96 m.In this tunnel,the length of outlet section is 760 m,its surrounding rock is soft and weak,the length of strengthened outlet section is 60 m,it is a soil tunnel.The paper narrates the concrete excavation and support methods of these two sections including excavation of upper and lower pilot drifts,arrangement of blast holes,installation of steel arch frames and anchors,concrete-guniting etc.