基于等效梁铰模型的盾构隧道上方卸载影响分析

Analysis of Unloading on Underlying Shield Tunnel Based on Equivalent Beam-Hinge Joint Model

国内城市出现诸多在地铁隧道上方开挖基坑的工程案例。由于地铁隧道对变形控制极为严苛,需准确评估上方卸载影响及应对变形控制措施。对装配式盾构隧道展开数值仿真分析,考虑管片接头,将隧道管片等效为梁铰接头模型;采用地层结构法,建立整体模型,土层采用HSS模型,分析基坑开挖对下卧盾构隧道的竖向隆起和径向收敛变形影响,并进一步分析采取隧道保护措施下的变形控制效果。结合工程实例分析表明:等效梁铰接头模型可以模拟出盾构隧道的径向收敛变形,得出上方卸载影响下隧道的“竖鸭蛋”变形姿态;在采取隧道变形控制措施下可有效控制隧道隆起量在1.5‰倍挖深以内。研究成果可为运营盾构隧道的监护管控提供指导。

There are many engineering cases of excavation of foundation pit above subway tunnel in domestic cities.As the extremely strict deformation control for subway tunnels,it is necessary to accurately evaluate the influence of unloading and the corresponding deformation control measures.Numerical simulation analysis of prefabricated shield tunnel is carried out,considering the influence of the segment joint,the tunnel segment is equivalent to the beam-hinge joint model.The ground-structure method is used to establish the overall model,and the HSS model is used to analyze the influence in excavation cases on the vertical uplift and radial convergence deformation of the underlying shield tunnel.Further the effect of deformation control is analyzed under tunnel protection measures.Combined with the engineering example,the research shows that the equivalent beam-hinge joint model can simulate the radial convergence deformation of shield tunnel and obtain the deformation attitude of“vertical duck egg”.With the tunnel deformation control measures,the tunnel uplift can be controlled within 1.5‰times the excavation depth.The research results can provide guidance for the monitoring and control of operating shield tunnels.