全风化花岗岩富水地层超大断面隧道设计技术

摘要

研究目的：在艰险困难山区，受铁路车站设置和联络线出岔影响，会出现多线车站隧道和变断面隧道，甚至形成超大断面隧道。当隧道位于软弱浅埋富水地层时，隧道建设存在以下安全风险：地形地质条件差，地下水发育，易坍塌破坏；初期支护受力大，变形控制难度大，存在变形侵限、失稳及塌方风险；隧道需采取多次开挖支护，受力转换困难，支撑拆换安全风险大。鉴于国内外软弱富水地层超大断面隧道实例不多、研究较少，本文结合实际工程，对此问题进行研究。研究结论：论文总结了国内外超大断面隧道修建技术现状，对隧道施工过程中的力学行为进行了分析，制定了隧道的超前支护措施、衬砌支护参数和施工方法，并得出如下主要结论：（1）软弱富水地层超大断面隧道修建难度大，安全风险高，造价高，需结合隧道工程的具体条件制定切实可行的支护措施和施工方法；（2）为控制软弱富水地层超大断面隧道初期支护变形和初期支护措施转换，采用大墙脚基础和多重支护措施是必要的；（3）为控制软弱富水地层变形，超大断面隧道变形及坍塌，应采取强有力的超前加固及掌子面加固措施；（4）该研究成果可为软弱地层超大断面隧道设计、施工提供借鉴。%Research purposes:In the dangerous difficult mountainous area,affected by the railway station setting and the contact line fork,there will be multi -line station tunnel and variable section tunnels,even form a super large section tunnel.When the shallow tunnel is located in stratum of completely weathered granite with abundant water, tunnel construction has the following security risks:the topographic and geological conditions are poor,developed groundwater,easy to collapse;Primary support force are large,deformation control is difficult,exit the risk of deformation intrude structure ambit,lose stability and collapse;Tunnel should be taken repeatedly excavation support, difficult force transfer,high security risk of support remove and replace.In view of the domestic and foreign less examples and research on super large cross section shallow tunnel in stratum of completely weathered granite with abundant water,there are less research on it.Based on the practical engineering,the problem is studied in this paper. Research conclusions:This paper summarizes the domestic and foreignnowadays construction technology of super large section tunnel,analyzes the mechanical behavior of tunnel constructive process,establishes measures of advanced support,support parameters of lining and constructive methods,the main conclusions are as follows:(1 )The construction of super large section tunnel in stratum of completely weathered granite with abundant water is difficult,high security risk and high cost,should be combined with specific conditions of tunnel engineering to develop practical supporting measures and construction methods.(2 )To control primary support deformation and primary supporting measures conversion of super large section tunnel in stratum of completely weathered granite with abundant water,large wall foundation and multiple supporting measures are necessary.(3 )In order to control deformation of soft stratum with abundant water, deformation and collapse of super large cross section tunnel, should adopt strong advanced reinforcement and reinforcement measures of tunnel face.(4)The relevant research results can provide reference for the design and construction of the super large section tunnel in soft stratum.