Investigation on the Influence Caused by Shield Tunneling: WSN Monitoring and Numerical Simulation

Traditional monitoring techniques are faced with the problems of low acquisition frequency and easy to be affected by the construction environment during the shield tunneling, which cannot meet the actual needs of timeliness monitoring of surrounding environmental impact on shield tunnel construction. Based on this actual demand, a wireless sensor network (WSN) system was used to monitor the response of shield tunnel segments and surrounding buildings during the shield tunneling in this study. According to the result of the signal transmission test, an optimization scheme of microelectromechanical system (MEMS) sensor layout is designed to improve the monitoring efficiency of the WSN system. Through the comparative analysis of WSN system monitoring data and traditional monitoring data, it is found that, with the increasing distance between the monitoring section and the tunnel face, the convergence value of tunnel lining clearance gradually tends to be stable, and the wireless monitoring results of transverse clearance convergence of the tunnel in this section are consistent with the overall deformation trend of the convergence gauge monitoring results. This study also simulated the shield tunneling adjacent buildings using a nonlinear finite element method. A parameter sensitivity analysis of the support pressure of the excavation face and the grouting pressure at the tail of the shield is carried out. The results show that the surface settlement can be reduced by properly increasing the grouting pressure and the support pressure of the excavation face. Moreover, increasing the support pressure of the excavation face has a better inhibition effect on the settlement of the surface soil than increasing the grouting pressure.

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