挤压性围岩单线铁路隧道受力变形分布规律研究及工程应用

挤压性围岩隧道大变形问题是近年来困扰隧道建设者的突出难题之一。以丽香铁路长坪隧道为工程依托,采用数值计算与现场测试相结合的方法,研究了挤压性围岩单线铁路隧道受力变形分布规律,并应用于工程实践。主要研究结论为:(1)单线隧道受洞室形状影响,变形以水平方向为主,围岩压力以垂直方向为主;(2)支护结构均以受压为主,拱腰和墙脚是易产生应力集中的薄弱环节,实测锚杆多受拉,墙中锚杆轴力远大于拱部及墙脚锚杆;(3)实测受力变形分布规律与计算结果基本一致;(4)工程实践中通过采取断面曲率优化、加长边墙系统锚杆、两台阶法开挖、高效锚杆钻机等措施,有效控制了围岩变形,隧道结构安全稳定。

Theoretical Analysis and Engineering Application of Stress and Deformation Distribution Law of Single Track Railway Tunnel in Squeezing Rock Conditions

The tunnel builders are puzzled by the tunnel squeezing rock problem in recent years.With the example of Changping Tunnel of Lijiang-Shangrila Railway,the author made a research on the distribution law of tunnel stress and deformation in squeezing rock by numerical calculation and field test methods.These research results are used in engineering practice.The main research results are as follows:(1) due to the shape of the tunnel,the deformation of the single track tunnel is mainly in the horizontal direction,and the surrounding rock pressure is mainly in the vertical direction.(2) The supporting structure is mainly subjected to compression.The arch waist and the wall foot are weak parts of stress concentration.The measured bolt axial force is tension,and the axial force of central wall bolt is much larger than that of the arch and the wall foot anchor.(3) The measured distribution law of stress and deformation is basically consistent with the calculation result.(4) In the actual tunnel construction process,the improved measures such as section curvature optimization,lengthening of the side wall system anchor,two-step method excavation,and high-efficiency anchor rig are adopted to effectively control the deformation of the surrounding rock and the tunnel structure is safe and stable.