Surface subsidence pattern of construction of pipe jacking in water-rich sand layer cross passage measured and numerical simulation analysis

This study elucidates the spatio-temporal dynamics of surface subsidence during the entirety of the pipe jacking construction process in water-rich sand layer cross passage. Initially, an analysis of the monitoring data of surface settlement was conducted. Subsequently, a three-dimensional soil-structure elastic-plastic model was established using finite element software to further investigate the spatio-temporal evolution of surface subsidence. The study findings suggest a strong correlation between the numerical simulation results and the measured data, thus reinforcing the model's credibility. As excavation advances, the settlement gradually accumulates, and upon removal of the equipment, the soil significantly rebounds, leading to a decrease in settlement. Surface settlement shows symmetry about the cross-passage's centerline, with the peak settlement (2.8 mm) located approximately 2 m from the starting point of the cross passage along its longitudinal profile. The concentrated settlement area closely resembles an elliptical shape. The settlement associated with the two excavation and hole-breaking stages exceeds that from other construction stages. These findings offer valuable guidance for the construction of subway cross passages in similar geological formations.