ABSTRACT
To improve the integrity, deformation resistance, and resilience of shield tunnels, and achieve sustainability goals, the prestress system has been introduced. However, research on the longitudinal mechanical characteristics of prestressed shield tunnels is lacking. To address this gap, a longitudinal non-uniform equivalent stiffness beam model (LNESBM) was developed. The new findings include: 1) Analytical solutions for longitudinal equivalent bending stiffness under two contact states of the circumferential seam were proposed, revealing a nonlinear decrease in bending stiffness as prestress reduces along the length. 2) Increasing steel strands enhances bending stiffness and radius of curvature, transitioning the circumferential seam from partially open to fully closed, improving flexural capability of the tunnel. 3) Compared to bolt connections, prestressed anchor cable connections significantly improve capacity, reduce longitudinal uneven deformation, and minimize circumferential seam opening.
