深埋隧洞围岩应力分布与破坏机理

Stress Distribution and Stress-induced Failures in Surrounding Rock Mass of Deep Tunnels

深埋隧洞围岩高应力破坏机理是研究深埋岩体力学特性和深埋地下工程实践中被关注的一个重要认识问题,深埋条件下围岩应力和围岩强度之间的矛盾更加复杂和典型,也成为认识问题的基本出发点。文章介绍了深埋隧洞开挖时不同部位围岩应力的变化路径;通过对比锦屏辅助洞出现的围岩破坏现象,分别论述了导致边墙松弛型破坏、应力集中部位的片帮破坏和岩爆破坏的围岩应力变化特征,在一定程度上解释了这些破坏的内在机理;并通过采用数值方法再现脆性围岩V型破坏形式,分析探讨了脆性围岩高应力破坏的局部化问题;指出了深埋岩石力学研究中的几个重要环节,如岩体力学特征的尺寸效应和应力路径效应等对准确认识深埋隧洞高应力破坏内在机理的重要意义。

Stress distribution and the mechanism of stress-induced failures in surrounding rock mass of deep tunnels have been a common concern in rock mechanics research for rock mass behavior and underground engineering practice.The relationship between stresses and rock mass strengths becomes critical and thus constitutes the basis for understanding rock mass behavior at great depth.This paper presents the stress paths showing stress altering at a few selected locations after excavating a tunnel at great depth.By comparing to the failures of rock mass observed in Jinping auxiliary tunnels,these stress paths can well explain the mechanism of sidewall failures as a kind of stress relaxation,spalling and rockburst as a result of stress induced rock mass yielding at different confinement levels.V-notch brittle failure was reproduced by numerical method and the localization of stress-induced failure of brittle rock at great depth is discussed.Meanwhile the study also involves the size effect and stress path effect,which plays a significant role to understand the inherent mechanism of rock mass failurs by high stresses under large overburden.