砂土地层隧道掌子面稳定性的物质点法分析  

Material Point Method Analysis for Stability of Tunnel Face in Sandy Stratum

作　　者：王明年 杨恒洪[1,2] 王旭 刘思杨 于丽 刘大刚 WANG Mingnian;YANG Henghong;WANG Xu;LIU Siyang;YU Li;LIU Dagang(State Key Laboratory of Intelligent Geotechnics and Tunnelling,Chengdu 610031,Sichuan,China;School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,Sichuan,China;National Center of Technology Innovation for Sichuan-Tibet Railway,Chengdu 610213,Sichuan,China)

机构地区：[1]极端环境岩土和隧道工程智能建养全国重点实验室,四川成都610031 [2]西南交通大学土木工程学院,四川成都610031 [3]川藏铁路技术创新中心有限公司,四川成都610213

出　　处：《隧道建设(中英文)》2024年第S2期74-84,共11页Tunnel Construction

基　　金：成都市科技计划项目(2022-XT00-00002-GX);中国国家铁路集团有限公司科技研究开发计划(K2023G041);国家自然科学基金项目(52378411)。

摘　　要：大型机械化隧道施工是保证隧道安全、高效、绿色掘进的有效施工方式。大型机械化施工往往配合采用全断面法开挖隧道,此时隧道掌子面开挖面积大、掘进速度快,容易出现掌子面失稳现象;而隧道掌子面的稳定性对隧道施工安全具有举足轻重的意义。通过引入物质点法来研究掌子面的稳定类型和变形特征,首先,通过模型试验结果对比验证物质点法数值模型,2种模型围岩的剪应变带在量级、范围和演化过程上都吻合良好;其次,考虑未支护段长度(L)、围岩黏聚力(c)和围岩摩擦角(φ),基于物质点法模型进行120种不同工况模拟。结果表明:1)隧道掌子面稳定性表现为掌子面稳定(稳定类型Ⅰ)、掌子面暂时稳定(稳定类型Ⅱ)和掌子面失稳(稳定类型Ⅲ)3种。其中,稳定类型Ⅱ的掌子面剪切带形态为抛物线形或椭圆+矩形,稳定类型Ⅲ为椭圆+对数螺旋形。2)c/D/γ和φ存在分界值(D为隧道直径),当c/D/γ≤0.09或φ≤11°时,不同L下的隧道面稳定类型均为稳定类型Ⅲ,L的增大导致稳定类型Ⅱ发生的可能性减小。The employment of large-scale mechanized tunnel construction represents an effective method to ensure the safety,efficiency,and environmental sustainability of tunnel excavation.Typically,this method involves full-face tunneling,characterized by large excavation areas and rapid excavation rates,often precipitating face instability.The stability of the tunnel face,consequently,holds paramount importance for the overall safety of tunnel construction.Accordingly,the authors introduce the material point method to the investigation of the various stability modes and failure characteristics of the tunnel face.Initially,the numerical model utilizing the material point method is validated through a comparative analysis with experimental results,revealing a strong concordance in the magnitude,extent,and evolution of shear strain zones within the surrounding rock across both models.Subsequently,considering factors such as the unsupported length(L),the cohesion(c)of the surrounding rock,and the friction angle(φ),a total of 120 distinct working conditions are simulated using the material point method model.The results indicate that:(1)The stability of tunnel face presents three modes,stable face(ModeⅠ),temporarily stable face(ModeⅡ),and unstable face(ModeⅢ).The failure mode for ModeⅡis characterized by a combination of parabolic or elliptical shapes with rectangular forms,while ModeⅢexhibits an elliptical shape accompanied by a logarithmic spiral.(2)A critical boundary exists between c/D/γandφ(where Drepresents the tunnel diameter andγrepresents the bulk density).When c/D/γ≤0.09 orφ≤11°,the stability mode of the tunnel face under varying Lconsistently aligns with ModeⅢstability.Moreover,an increase in Lcorrelates with a reduced likelihood of encountering ModeⅡstability.

关 键 词：砂土地层 隧道掌子面 未支护段长度 物质点法 稳定类型 变形特征 

分 类 号：U45[建筑科学—桥梁与隧道工程]