Impact of shield tunneling on deformation of overlying existing tunnels considering jacking force effect

Abstract

Abstract In order to investigate the influence of shield tunneling on the deformation of overlying existing tunnels, a predictive analytical method for the deformation response of existing tunnels is proposed. The modified Loganathan formula is used to analytically obtain additional stresses at the axis of the existing tunnel caused by tunnel excavation underlying. The existing tunnel is simplified as an infinite Timoshenko beam supported on a Winkler foundation. The influence of jacking force in the existing tunnel is introduced, and analytical solutions for stress and deformation responses of the existing tunnel are obtained by considering boundary conditions at both ends. The research results indicate that the calculated results closely match measured data from existing literature, and the proposed method shows superiority compared to the T-W and EB-W models with degenerate capabilities. Further parameter analysis concludes that the shear stiffness of the existing tunnel is not a sensitive factor to tunnel displacement changes, but the change in jacking force is crucial. The jacking force in the existing tunnel is a significant factor affecting the response of existing tunnel. Both the deformation and inner forces of the existing tunnel linearly increase with the increase of the ground loss rate.