特长深埋隧道合修与分修对岩爆的影响研究

Study of the Impact of Single-and Double-tube Tunnel Systems on Rockburst in Deep-buried Extra-long Tunnelling

在高地应力环境下进行隧道开挖,岩爆是最主要的灾害之一,以成兰铁路平安隧道高地应力岩爆段为研究对象,采用现场实测、数值分析、室内试验等手段,从岩爆孕育机理、能量密度变化、岩爆强度等方面,全面分析了高地应力环境下合修与分修两种建设方案对特长深埋隧道岩爆的影响。研究结果表明,隧道各位置的最大能量密度的关系为U_(边墙)>U_(拱腰)>U_(掌子面)>U_(拱顶);岩爆易发生于掌子面待循环开挖段及开挖支护段的两侧;相比于拱顶、拱腰、边墙等位置,掌子面处会发生较大的能量释放,在开挖过程中应合理设置应力释放孔;采用隧道分修的建设方案能够有效降低岩爆的强度,减小岩爆的危害,从而更好地避免岩爆发生。

Rockburst is one of the main disasters for tunnelling under high ground stress.Taking the rockburst sec⁃tion of Ping′an Tunnel with high ground stress,which is located on Chengdu-Lanzhou Railway,as the study object,this paper adopts combined methods of filed measurement,numerical analysis,and laboratory test,and with respect to rockburst development mechanism,energy density change and rockburst strength it comprehensively analyzes the impact of two construction schemes(single-tube double-track tunnel system and double-tube single-track tunnel system)on the rockburst in deep-buried extra-long tunnels with high ground stress.The study results show that the order relation of maximum energy density at various locations of the tunnel is U_(side wall)>U_(hance)>U_(tunnel face)>U_(vault),and rockburst easily occurs at the working face of the tunnel section to be excavated and both side walls of excavated and supported section;compared with vault,hance,side wall and other locations,more energy would be released at the tunnel face,and the stress release holes shall be reasonably installed in the process of excavation;the doubletube single-track tunnel system scheme can effectively reduce the rockburst intensity and the rockburst hazards,so as to better avoid the occurrence of rockburst.