Behavior of damaged TBM tunnel under MJS and Micro-disturbance grouting treatment: a case study

The operating subway tunnel is often damaged due to excessive deformation in China. In order to ensure the safe for operation, remediation and protection measures must be taken, especially in soft soil areas. This paper presents a case study on remedial scheme of damaged TBM (Tunnel Boring Machine) tunnel adjacent to excavation combining with MJS (Metro Jet System) and micro-disturbance grouting technology in Hangzhou, China. The track bed settlement, horizontal displacement and convergence of the TBM tunnel caused by MJS and micro-disturbance grouting construction were analyzed and discussed. The results showed the characteristics of soil layer under the tunnel have significant influence on the treatment effect. Even if multiple grouting was adopted, the treatment failure may occur under the combination action of external loads such as traffic load or surcharge load, which should be considered when civil engineers design remediation scheme. The results can provide practical experience and guidance for similar treatment scheme of damaged TBM tunnel.