Prediction and Analysis of Subsurface Settlement in a Double-Line Shield Tunnel

The original stress equilibrium state of the soil is destroyed after the excavation of the double-line shield tunnel, resulting in the settlement of the stratum above the tunnel and bringing adverse effects on the surface buildings and subsurface pipelines near the tunnel. The reasonable prediction of subsurface settlement is significant for protecting adjacent underground structures. The wave propagation model is introduced to describe the settlement mechanism of the stratum above the tunnel based on random medium theory, and the subsurface settlement model of single-line tunnel is derived through the Fourier transform. The disturbance influence factor of double-line tunnel is defined, and the corresponding settlement model is established. The three-dimensional subsurface settlement models of single-line and double-line shield tunnels are proposed by introducing the surface displacement release rate of palm surface and maximum slope of surface vertical settlement. The models are verified using monitoring data, and the effects of the parameters on the model are analyzed.