隧道围岩稳定性及其支护作用分析

Analysis of surrounding rock stability and support action in tunnels

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.

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,synergistic action of supporting structure system.Firstly,based on statistical analysis of abundant monitoring results in mountain tunnels,this paper put forward some general rules and basic characteristics of surrounding rock deformation.Taking deformation accelerating place of tunnel surface,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 concept 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 surrounding 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 synergistic action of preliminary reinforcement layer and subsequent support layer.The research conclusions are of great significance for the realization of dynamic and quantitative design as well as construction of tunnel engineering.