Stability Analysis of the Surrounding Rock of a Super-Large Diameter Shield Tunnel in Karst Strata

Based on the tunnel project at the south extension of Wuhan Heping Avenue (Zhongshan Road-Zhangzhidong Road), finite element analyses are conducted to analyse the deformation and stress characteristics of the surrounding rock and the lining of a super-large diameter shield tunnel passing through karst strata and the effect of the ground loss during the shield construction process on the stability of the karst caves and the surrounding rock of the tunnel is discussed. Analysis results show that when the diameter of the karst cave is large, the deformation of the tunnel moves towards the location of the karst cave and the local region of the tunnel close to the karst cave bears a greater force, which should be paid more attention to in the engineering practice. Results also show that the karst cave above the tunnel increases the maximum settlement of the ground surface and may lead to ground subsidence and other engineering disasters. During construction, small ground loss should be ensured as large ground loss will result in obvious ground subsidence. The research outcomes from this study can be used as a reference for similar engineering projects.