大跨扁平极软岩隧道大变形结构处理分析  

An analysis of Large Deformation Structure Treatment for Large-Span Flat Soft Rock Tunnel

作　　者：王万平[1] 李建斐[1] 辛讲合 别素平 WANG Wanping;LI Jianfei;XIN Jianghe;BIE Suping

机构地区：[1]中交第一公路勘察设计研究院有限公司,西安710075

出　　处：《公路交通技术》2018年第B09期45-51,共7页Technology of Highway and Transport

摘　　要：牛头山隧道为双向6车道大跨度隧道,当开挖至绿泥石云母片岩段时发生了严重的大变形,拱顶最大下沉达1.6 m。为解决极软岩隧道大变形问题,通过对大变形围岩和初支变形特征、发生原因的分析,确定了"分台阶大预留、快开挖、双层强支护、早封闭"的大变形处理原则和方案。施工期间通过对双侧壁、单侧壁法和三台阶法施工的现场实践,证明依托工程采用短台阶开挖工法控制围岩大变形具有十分显著的效果。在确定采用三台阶开挖方法后,对拟定的应力释放层扩挖+双层H型钢初期支护和双层H型钢初期支护+108锁脚钢管两种支护方案,在左右洞进行了平行试验,结果发现采用双层H型钢支护+108锁脚钢管对于控制大变形效果良好,最终采用该方案顺利完成了绿泥石片岩段施工。Niutoushan Tunnel is a bidirectional six-lane tunnel with a large-span. When it is excavated to the chlorite mica schist section, serious large deformation occurs and the maximum settlement of the vault is 1. 6 meters. In order to tackle the large deformation of tunnel in extremely soft rock, the principle and scheme of large deformation treatment of ＂ large reserved step, quick excavation, double-layer strong support and early closure＂ are adopted by analyzing the deformation characteristics and causes of large deformation surrounding rock and initial support. The field practice of double side wall, single side wall and three-step method during construction proves that the short-step excavation method can control the large deformation of surrounding rock effectively. After adopting the three - step excavation, the two supporting schemes of stress-relief layer expansion plus double-layer H-beam initial support and double-layer H-beam initial support plus 108 pinned steel pipes were tested in the left and right tunnels. The results show that the double-layer H-beam support plus 108 pinned steel pipe has a good effect on controlling large deformation. Therefore, the project has successfully completed the construction of green shale section by the double-layer H-beam support plus 108 pinned steel pipes.

关 键 词：大跨度隧道 极软岩 大变形 处理措施 

分 类 号：U455.72[建筑科学—桥梁与隧道工程]