Influence of undercrossing tunnel excavation on the settlement of a metro station in Dalian

Abstract

Numerous tunnel excavation projects have been undertaken in China to address the ever-increasing demand for tunnels, which is driven by the rapid development of urban cities. Tunnel excavations generally induce the settlement of existing tunnels and sometimes result in the derailment of metro vehicles. In this study, the Nanyan Fourth Circuit Transmission Reconstruction, located in Dalian City in China, was selected to investigate the local settlement of a metro station caused by an underlying tunnel excavation project. The theoretical solution of the stochastic medium theory was calculated for a horseshoe-shaped tunnel based on the Gauss–Legendre integral in a non-uniform convergence situation. Results were compared with data measured at the metro station. A three-dimensional model was developed to further explore the variations in stress and deformation, which were difficult to measure during the excavation. The results showed the existence of a settlement gradient of the metro station in the direction of the excavation after the underlying tunnel was excavated. The numerical results were in good agreement with the data measured onsite. The non-uniformity of the settlement in the direction of the excavation was investigated. The findings of this study can provide a reference for predicting and controlling the impact of undercrossing tunnel excavation on the deformation of metro stations.