隧道围岩稳定性及其支护作用分析

针对隧道设计中的围岩力学特性及其荷载效应、"支护-围岩"动态作用特点及支护结构体系的协同作用原理3个基本问题进行研究.首先基于对大量山岭隧道围岩变形监测结果的统计分析,指出围岩变形规律和基本特点,以隧道掌子面围岩变形加剧点、初期支护施作和围岩变形稳定作为3个关键节点对"支护-围岩"力学演化过程的作用特点进行分析.提出了"浅层围岩"与"深层围岩"组成复合围岩结构的新理念,对围岩失稳的动态特征进行阐述,并通过计算分析指出了隧道围岩失稳模式、失稳机理和失稳范围的确定方法.基于围岩失稳模式推导作用于支护结构的围岩荷载计算公式,它包括由浅层围岩确定的"给定荷载"和深层围岩传递的"形变荷载"两部分.建立支护结构体系的协同作用力学分析模型,分析了弹塑性条件下影响塑性区变化的关键因素,揭示了初步加固圈层与后续支护圈层的协同作用原理.研究结论对实现隧道工程的动态化、定量化设计和施工具有重要的指导意义.

Analysis of surrounding rock stability and support action in tunnels

This paper is aimed at three basic problems in tunnel design:mechanical characteristics and load effect of surrounding rock,dynamic interaction of support and surrounding rock,syner-gistic action of supporting structure system.Firstly,based on statistical analysis of abundant mo-nitoring results in mountain tunnels,this paper put forward some general rules and basic charac-teristics of surrounding rock deformation.Taking deformation accelerating place of tunnel sur-face,application of initial supporting and secondary lining as three key nodes,this paper analyzed the mechanics evolution process of support and surrounding rock interaction.Then,a new con-cept was put forward in this paper:Shallow buried and deep buried surrounding rock form the composite surrounding rock structure.Through calculation and analysis,this paper described the dynamic characteristics of surrounding rock failure,and presented a method for determining the mode,mechanism and range of surrounding rock failure.By analyzing surrounding rock failure mode,this paper proposed that load effect is composed of given pressure from shallow buried sur-rounding rock and deformation pressure from deep buried surrounding rock,and then a formula for calculating the surrounding rock load acting on supporting structure is derived.Last of all, this paper established a mechanical model of the supporting structure system,analyzed the key factors that influence plastic zone development under elastoplastic model,and revealed the syner-gistic action of preliminary reinforcement layer and subsequent support layer.The research con-clusions are of great significance for the realization of dynamic and quantitative design as well as construction of tunnel engineering.