The impact of TBM EPB tunnelling was assessed with respect to the observed values of settlements as the results of extensive monitoring system of the subsoil and ground surface. The aim of the analysis using empirical methods was to determine the real scale of impact and to determine the formula for the asymmetric subsidence trough observed during the passage of two TBMs in quaternary cohesive soils. Based on field measurements, authors propose the polynomial formulation for the depth and shape of the asymmetric subsidence trough prediction over twin tube TBM tunnel.

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.

In order to study the influence of multiple karst cave factors on surface settlement during tunnel boring machine (referred to TBM hereinafter) tunnelling, a three-dimensional numerical model is built by taking a subway project as an example and combining it with MIDAS GTS NX finite element software. Secondly, the influence of the radius, height, angle, vertical net distance and horizontal distance of the karst cave on maximum surface settlement is studied and sorted under the two working conditions of treatment and lack of treatment using the gray correlation analysis method. Additionally, a multi-factor numerical model of the untreated karst cave is established. Finally, based on the preceding research, a multi-factor prediction model for maximum surface settlement is proposed and tested. The results reveal that when the karst cave is not treated, the radius and height of the karst cave have a significant effect on maximum surface settlement. Following cave treatment however, the influence of the cave parameters on maximum settlement of the surface is greatly reduced. The calculating model created in this study offers excellent prediction accuracy and good adaptability.