小曲率半径隧道盾构施工的地表沉降规律分析——以南昌地铁1号线为例

为探究小曲率半径隧道盾构施工引起地表沉降的变化规律,利用Mindlin解建立小曲率半径隧道盾构施工引起地表沉降的解析计算模型,以南昌地铁1号线盾构隧道工程为依托,通过与现场监测和已有Mindlin解析计算模型的对比分析,验证本文所建立沉降预测模型的合理性,并依次从盾构附加推力、盾壳不均匀摩擦力和地层损失对地面变形的影响进行分析。结果表明：本文所建立的小曲率半径隧道盾构施工引起的地表沉降解析计算模型可有效应用于实际隧道工程的沉降预测,提高了预测精度;盾构开挖过程中,横断面地表沉降槽呈V形,近似正态分布,施工产生的地层损失对地面沉降的影响更大;随着盾构路径两侧推力及摩擦力分布不均程度的增加,地面沉降槽中心偏移情况而增大,地面沉降与地层损失呈非线性相关。研究结果可为类似拟建和在建盾构隧道工程提供理论指导与参考。

Analysis of Surface Settlement Pattern of Shield Construction in the Small Curvature Radius Tunnel

In order to investigate the changes of surface settlement caused by shield construction in small curvature radius tunnel, an analytical calculation model of surface settlement caused by shield construction in small curvature radius tunnel was established by using Mindlin solution, and the reasonableness of the settlement prediction model established was verified by comparing and analyzing with field monitoring and existing Mindlin analytical calculation model based on the shield tunnel project of Nanchang Metro Line 1. The results of this study show that the additional thrust of the shield, the uneven friction of the shield shell, and the ground deformation of the ground loss are analyzed in turn. The results show that the analytical calculation model of ground settlement caused by shield construction in small curvature radius tunnels can be effectively used for the prediction of ground settlement in actual tunnelling projects, and the prediction accuracy is improved. During the shield excavation process, the cross-sectional ground settlement trough is "V" shaped and approximately normally distributed, and the ground settlement is more influenced by the stratum loss generated by the construction. With the increase of uneven distribution of thrust and friction force on both sides of the shield path, the offset of the center of the ground settlement trough increases, and the ground settlement is nonlinearly related to the ground loss. The results of the study can provide theoretical guidance and reference for similar proposed and under-construction shield tunnel projects.