三台阶七步法施工高地应力隧道支护结构受力特性分析  

Analysis of the Force Applied on the Support Structure in a High-Geostress Tunnel Constructed by the Three-Bench Seven-Step Method

作　　者：张德华[1] 刘士海[2] 任少强[3] 

机构地区：[1]北京交通大学土木建筑工程学院,北京100044 [2]北京市市政工程研究院,北京100037 [3]中铁二十局集团有限公司,西安710016

出　　处：《现代隧道技术》2016年第1期96-102,110,共8页Modern Tunnelling Technology

摘　　要：文章以兰新铁路大梁山高地应力隧道为工程背景,展开三台阶七步法施工高地应力隧道支护结构受力特性研究。通过现场监测及三维数值仿真模拟,对施工过程中的围岩-初期支护接触压力、拱架所受的拉压应力及变形规律进行系统研究。现场监测及数值分析结果表明:(1)支护结构变形均基本满足设计规定的沉降控制指标(350 mm)及《铁路隧道设计规范》对沉降、收敛的相关要求;(2)围岩-初期支护接触压力及支护结构变形值均随着工序开展而不断增加,最大值均出现于侧墙拱腰部位,其中接触压力最大值为845.8 k Pa,收敛最大值为365 mm;(3)初期支护的最小主应力σ3逐渐增大并全部表现为压应力,其绝对值大于最大主应力;最小主应力σ3在仰拱闭合后各点基本达到最大值,趋于稳定;(4)高地应力隧道开挖过程中围岩将产生较大塑性区,拱肩及拱底部位发展最快,仰拱封闭是变形控制的关键点。因此,施工时应加快初期支护封闭成环,以减小应力增加,增强初期支护安全性。Using the Daliangshan tunnel on the Lanzhou-Xinjiang railway as an example, and based on field moni- toring and 3D numerical simulation, an analysis of the force applied on the support was carried out for the high-geo- stress tunnel constructed by the three-bench seven-step method, focusing on the contact pressure between the pri- mary lining and surrounding rock, the tension-compression stress applied on the steel arch and relevant deformation rules. The results show that： 1） the lining deformation is basically within the scope of the designed settlement control index of 350 mm and the requirements related to settlement and convergence in the Code for Design of Railway Tun- nel; 2） the contact pressure and the deformation of the primary lining may increase with the construction steps, and both maximum values occur at the haunch of the sidewall, of which the maximum contact pressure is 845.8 kPa and the maximum convergence is 365 mm; 3） the minimum principal stress 0＂3 of the primary lining gradually increases with all behaviors as compressive stress, with an absolute value that is greater than the maximum principal stress; 4） the minimum principal stress 0＂3 of each point reaches its peak and later becomes stable after closure of the invert; and 5） large plastic zones may occur during tunnelling, of which the spandrel and the tunnel bottom have the rapidest plastic development, showing that invert closure is the key to deformation control. Thus, it can be seen that the primary support should be closed as early as possible during construction so that the increase of stress can be re- duced and safety can be improved.

关 键 词：高地应力隧道 初期支护 三台阶七步法 受力特性 现场试验 

分 类 号：U451[建筑科学—桥梁与隧道工程]