大断面黄土隧道双侧壁导坑法施工诱发地表沉降及隧道变形规律研究

以西安地铁3号线某区间双侧壁导坑法隧道工程为依托,采用FLAC3D模拟与现场实测相结合的方式,研究双侧壁导坑法施工引起的地表及隧道变形规律。研究结果表明:地表横向沉降曲线关于隧道中轴线对称分布,影响范围左右各30 m,可见,上导洞的开挖是造成地表沉降的主要原因;采用超前小导管注浆加固土体,有效控制了拱顶下沉;隧道开挖后两帮收敛值迅速增大,开挖面超前监测断面20m时收敛趋于稳定;模拟结果与实测数据吻合较好,说明FLAC3D数值模拟软件能有效预测地层变形。

Settlement Laws of Ground and Tunnel Deformation Induced by Construction of Large Section Two-side Wall Drift Heading Method Tunnel in Loess Region

Based on two-side wall drift heading method tunnel construction in Xi'an metro Line 3 project,the settlement laws of ground face and tunnel deformation induced by construction in loess region are studied by using FLAC3D numerical simulation and field measurement.The research shows that the curves of the surface crosswise settlement are symmetrical around the axis of the tunnel,the sphere of influence is 30 m on each side.The main reason of the surface subsidence is considered as the excavation of the upper pilot tunnel,and it is effective to control the vault settlement by using advanced small pipe grouting soil.The convergence value of pilot tunnel grows rapidly after the excavation of the tunnel,but tends to stabilize when the tunnel face advancing leads the monitoring section 20 meters.Numerical simulation results are consistent with the measured data,it is clear that the FLAC3D numerical simulation software can predict ground deformation.