新建路基开挖换填对下方既有盾构隧道影响研究

依托南京市某市政道路上跨既有超大直径盾构隧道工程，分别采用二维梁-弹簧法与三维有限元法对路基开挖与回填等工况进行数值模拟，分析了不同工况下既有盾构隧道衬砌结构的受力与变形情况，并对其安全性进行评估。结果表明:新建路基换填采用轻质泡沫土的处理方式安全可行；既有盾构隧道结构受力及变形均在规范允许范围内；新建路基工程不会对下方的盾构隧道结构造成安全影响。

Study on Influence of Excavation and Replacement of Newly-built Subgrade on Existing Shield Tunnel underneath

Based on an existing super-large diameter shield tunnel project on a municipal road in Nanjing, two dimensional beam-spring method and three dimensional finite element method have been adopted to simulate the excavation and back-filling of subgrade respectively. The stress and deformation of the lining structure of the existing shield tunnel under different working conditions have been analyzed, and the safety of the tunnel has also been evaluated. The results show that it is safe and feasible to replace the newly built roadbed with light foamed soil; that the force and deformation of the existing shield tunnel structure are within the allowable range of the code; and the new roadbed works will not affect the safety of the shield tunnel structure underneath.