特大断面隧道组合钢模衬砌施工技术
Construction Technology of Combined Steel Formwork Lining of Super Large Section Tunnel

隧道工程地质条件复杂、开挖难度大，尤其是特大断面隧道开挖工程，为了保证施工安全性，需要选择合适的支护结构。本文以贵安新区浅埋软岩特大断面隧道群项目为工程背景，在确保安全的前提下，为了提高施工进度，采用小断面变大断面进行开挖，选用组合钢模衬砌作为特大断面隧道开挖的支护结构。利用朗肯土压力理论计算得到了不同埋深隧道围岩垂直压力、水平压力，设计了组合钢模衬砌结构参数。通过隧道围岩两帮位移和拱顶沉降位移监测结果，变形量在控制范围内，对围岩的扰动小，表明选用的组合钢模衬砌结构能有效的控制隧道围岩的变形，采用的工作原理及工艺流程是可行的，确保了隧道施工进度和安全。此次施工技术和方法可为类似工程提供借鉴。
The tunnel engineering geological conditions are complex and difficult to excavate, especially for the excavation of large-section tunnels. It is necessary to select suitable supporting structures for ensuring the construction safety. In this paper, the shallow-buried soft rock super-large section tunnel group project in Gui’an New Area is taken as the engineering background. Under the premise of the construction safety and the construction schedule requirements, the small section is changed into a large section for excavation, and the combined steel formwork lining is selected as the supporting structure for excavation of the extra large section tunnel. The vertical pressure and horizontal pressure of surrounding rock of different buried depths tunnels are calculated by using Rankine earth pressure theory, and the structural parameters of combined steel formwork lining are designed. Through the monitoring results of the displacement and arch settlement of the sur-rounding rock of the tunnel, the deformation is within the control range and the disturbance to the surrounding rock is small, which indicates that the selected composite formwork lining structure can effectively control the deformation of the surrounding rock of the tunnel. This shows that the principle and process are feasible, which can ensure the progress and safety of the tunnel con-struction. The construction techniques and methods can provide a reference for similar projects.