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一、前言引滦入津输水工程中最关键的工程是隧洞,总长11.39km,其中暗挖隧洞9680m,明挖隧洞1710m,它是我国目前最长的输水隧洞。隧洞净宽5.7m,净高6.25m,设计流量60m~3/s,校核流量75m~3/s。隧洞东段由进口桩号0+268至横河出口桩号2+730,该段长2462m,穿越进口洞口段、P_4断层破碎带、f_(74)、F_(18)、F_(20)、F_(16)、F_(14)、F_(34)断层等软弱破碎围岩。由中国人民解放军五二八五九部队承担施工。本文着重介绍采用正台阶大断面开挖、光面爆破和锚喷(网)支护用于隧洞进口段软弱破碎围岩的施工方法。该段处于全、强风化层内,洞顶复盖层较薄,最薄处为8m(为洞跨1.1倍),
I. INTRODUCTION The most crucial project in the water transfer project from Luan River to Tianjin is a tunnel with a total length of 11.39km, of which 9680m of underground excavation tunnels and 1710m of open-cut tunnels are the longest tunnels for water diversion in our country. The tunnel has a clear net width of 5.7m and a net height of 6.25m. The designed flow rate is 60m 3 / s and the check flow rate is 75m 3 / s. The east section of the tunnel is composed of entrance stake 0 + 268 and Yokogawa exit stake 2 + 730, which is 2462m in length. It traverses the entrance of Dongkou Port, the fault zone of P_4, f_ (74), F_ (18), F_ (20) F_ (16), F_ (14), F_ (34) faults and other weak broken rock. The Chinese People’s Liberation Army 5,259,9 troops assumed construction. This article focuses on the use of positive step large section excavation, smooth blasting and anchor spray (mesh) support for the tunnel entrance section of weak broken rock construction method. The section is in the whole, strong weathering layer, the top of the tunnel cover thinner, the thinnest at 8m (for the hole span of 1.1 times)