富水卵石地层下明挖法基坑施工对老旧隧道变形分析
Deformation Analysis of old Tunnels by Cut-and-Cover Method Foundation Construction under Water-Rich Pebble Strata

隧道采用明挖法近接既有老旧隧道施工具有较强的不确定性，在富水卵石地层难以控制既有构筑物变形。本文采用MIDAS GTS NX建立三维有限元模型，分析在富水砾砂地层下，明挖法基坑施工对老旧隧道的影响，通过优化降水步骤、注浆方法和地层加固技术减小既有构筑物变形。结果表明，基坑开挖对隧道竖向变形影响远大于水平变形，最大沉降为7.78 mm，既有隧道靠近注浆加固区的中心区域沉降较小，为3.01 mm，表明基坑底部注浆具有良好的加固作用。研究成果为类似的老旧隧道近接施工提供了有益的工程参考。
Tunnel construction using cut-and-cover method close to the existing old tunnel has strong uncertainty, and it is difficult to control the deformation of existing structures in the water-rich pebble stratum. In this paper, MIDAS GTS NX is used to establish a three-dimensional finite element model to analyze the impact of cut-and-cover tunnelling on old tunnels in water-rich gravel-sand strata, and to reduce the deformation of existing structures by optimizing the descending steps, grouting methods and ground reinforcement techniques. The results show that the impact of pit excavation on vertical deformation of the tunnel is much larger than the horizontal deformation, and the maximum settlement is 7.78 mm, and the settlement in the center area of the existing tunnel near the grouting reinforcement area is smaller, 3.01 mm, indicating that the grouting at the bottom of the pit has a good reinforcing effect. The research results provide a useful engineering reference for the construction of similar old tunnels in close proximity.