双连拱隧道施工阶段衬砌裂损状态成因的研究

文章针对双连拱隧道施工期间衬砌裂损出现的过程、状态、分布特点及现场处置,综合现场勘查、施工过程分析、地形地质等因素,定性研究了衬砌致裂成因,建立了隧道进口衬砌裂损区段施工过程数值分析模型；考虑隧道所处位置实际地形条件、围岩构造参数、实际施工工序等,重点研究了衬砌结构内主应力的分布规律.研究结果表明,衬砌裂损的主要成因是偏压荷载作用造成局部应力大于正常设计承载力；由于地质构造复杂,施工中考虑不周、对塌方区处理固结不充分,加之施工中多次扰动、左右线相互影响等,使围岩松动软化.文章从理论上解释了该隧道衬砌裂损产生的机理,其结果与现场实际相吻合.

Research on the Origins of Lining Cracks in Double-Arch Tunnels During Construction

This paper discusses the genesis of lining cracks in a double-arch tunnel during its construction.A qualitative analysis of the process,status,distribution and site treatment of crack damage was performed based on a site investigation,the analysis of construction process and the factors of topography and geology.In addition,this paper establishes a numerical model for analyzing the construction of the tunnel portal section with lining damage.Furthermore,it focuses on the distribution law of main stress inside of the lining structure considering the topographic conditions,parameters of the surrounding rock structure and construction procedures.Results show that the load is larger than the designed one locally due to bias load and that the geological structure is complex;the surrounding rock is loosening since the reinforcement is not adequate at the collapse area and it was disturbed often during the construction.All of these factors result in lining cracking.This paper theoretically explains the cracking mechanism and describes how it is consistent with the actual conditions.