Study on the convergence mode of shield tunnel section during proximity pile foundation excavation

To reveal the deformation characteristics of soil in the shield tunnels section during proximity pile foundation excavation and to establish the convergence model for the tunnel excavation section. A model test of shield tunnel excavation adjacent to piles was carried out in this paper. Based on the data collected using a developed monitoring device for soil displacement in the tunnel section，the soil deformation law of excavation section under various conditions was analyzed. Additionally，a loss contour for the tunnel section exhibiting a non-uniform convergence mode was proposed. A mapping function expression for the Laurent series of the tunnel excavation loss section was established based on the theory of complex functions. The results indicated that the deformation of the tunnel arch bottom lagged behind that of the tunnel vault，and the deformation of the soil around the tunnel section was restrained by the adjacent piles. Comparisons between the calculated and measured values were made to evaluate the validity of the mapping function expression for the tunnel excavation loss section.