Research on the mechanical model and support optimization of deep cover vertical shaft based on the coupling effect of interlocking pile wellbore system

Artificial ground freezing is a widely adopted method in vertical shaft construction. However, its applicability becomes limited under complex geological conditions in deep topsoil layers, where it may lead to structural failures, such as shaft collapse and groundwater ingress. To address these challenges, this study investigates the deep shaft construction project in the Wucaiwan region and proposes a coupled structural model that considers the interaction between interlocking piles and shaft lining. A theoretical formulation for calculating the required lining thickness is also derived based on thick-walled cylinder mechanics. Numerical simulations using Midas GTS are conducted for various combinations of interlocking pile diameters and lining thicknesses. The results indicate that increasing the lining thickness offers more effective deformation control than enlarging the pile diameter. In addition, the presence of underlying rock strata significantly reduces the vertical displacement of the shaft lining. These findings provide a theoretical and numerical basis for optimizing shaft support systems in deep and complex soil environments.