双护盾TBM施工隧道豆砾石回填层对地表沉降影响机理  

Influence Mechanism of Pea Gravel Backfill Layer on Surface Subsidence in Tunnel Construction with Double-Shield TBM

作　　者：吴圣智 王明年[2] 李磊[3] 王军[1] WU Shengzhi;WANG Mingnian;LI Lei;WANG Jun(School of Civil Engineering,Shandong Jianzhu University,Jinan Shandong 250101,China;School of Civil Engineering,Southwest Jiaotong University,Chengdu Sichuan 610031,China;Bridge and Tunnel Research Center,Research Institute of Highway Ministry of Transport,Beijing 100088,China)

机构地区：[1]山东建筑大学土木工程学院,山东济南250101 [2]西南交通大学土木工程学院,四川成都630031 [3]交通运输部公路科学研究院桥梁隧道研究中心,北京100088

出　　处：《中国铁道科学》2020年第4期82-90,共9页China Railway Science

基　　金：国家自然科学基金资助项目(51704176)。

摘　　要：采用双护盾TBM施工浅埋隧道时,管片壁后吹填豆砾石至注浆前地表会出现较大的持续沉降。针对该问题,采用现场实测、土工试验和连续单元—离散单元耦合算法,分析施工过程中地表沉降规律及豆砾石回填层对地表沉降的影响机理。结果表明:受豆砾石状态影响,地表沉降可分为超前沉降、快速沉降、持续沉降和稳定4个阶段;豆砾石单位充填体积越小,持续下沉阶段地表沉降占总沉降比例越大;豆砾石的抗压缩变形能力与其孔隙率成反比,管片壁后豆砾石在未压实之前,无法有效地为围岩提供支撑;豆砾石颗粒自上而下的迁移能改变管片壁后豆砾石孔隙率分布,降低隧道顶部围岩受到的支护力,并为地层损失提供空间,导致地表沉降增加。根据青岛地铁双护盾TBM施工隧道实际工程,将豆砾石充填状态分为密实、变形后密实、始终不密实3类,并给出其单位充填体积的建议值。When the shallow tunnel was constructed by double-shield TBM,the surface would continue to settle after the pea gravel was hydraulically filled behind the segment until grouting.In order to solve this problem,the field measurement,geotechnical test and the coupling algorithm of continuous element and discrete element were used to analyze the law of surface settlement during construction and the influence mechanism of pea gravel backfill layer on surface settlement.Results show that,affected by the status of pea gravel backfill,the surface settlement can be divided into four stages:advance settlement,rapid settlement,continuous settlement and stability.The smaller the unit filling volume of pea gravel,the larger proportion of surface settlement to total settlement in the continuous settlement stage.The compressive deformation resistance of pea gravel is inversely proportional to its porosity.The pea gravel behind the segment cannot effectively support the surrounding rock before compaction.The migration of pea gravel from top to bottom can change the porosity distribution of pea gravel behind the segment,which can reduce the support force on the surrounding rock at the top of the tunnel,provide space for the formation loss,and lead to the increase of surface settlement.Based on the actual construction of double-shield TBM tunnel in Qingdao Metro,the filling state of pea gravel can be divided into three categories:dense,dense after deformation and not dense at all.The recommended value of unit filling volume is given.

关 键 词：隧道 双护盾TBM施工 豆砾石回填层 地表沉降 孔隙率 单位充填体积 

分 类 号：U455.43[建筑科学—桥梁与隧道工程]