Settlement and deformation monitoring and spatio-temporal data interpolation method for urban ultra long subway tunnels under soft soil foundation

: [Objective] Precise monitoring of settlement and convergence deformation in urban subway tunnels is crucial for ensuring operational safety and the stability of the surrounding environment. Traditional methods, such as manual inspections and fixed sensor monitoring, suffer from poor real-time performance and limited data availability. [ Methods] To address the limitations of traditional approaches, an innovative wireless sensor network (WSN) monitoring system is introduced in this study by taking the East Extension Section of Shanghai Metro Line 2, a large-scale urban underground tunnel constructed using shield technology in soft soil as the example. Additionally, a missing value imputation algorithm tailored to WSN characteristics is proposed to address the potential data gaps in WSN monitoring which may arise in the following 8-year monitoring period. [Results] The implementation of this monitoring network and algorithm provides full data and characteristic indicators for the tunnel monitoring, which aids in revealing the influencing factors of lateral convergence deformation in shield tunnels constructed in soft soil. [Conclusion] By ensuring the effectiveness and completeness of the monitoring data, this research offers technical sup