Peridynamic simulation on crack propagation and mechanical properties of tunnel linings with cracks

Crack propagation critically threatens the structural integrity of urban underground tunnel linings. This study employs an integrated experimental and numerical methodology, combining scaled model tests with peridynamic (PD) simulations, to investigate cracking mechanisms and quantify the effects of pre-existing cracks in a case study of Beijing Subway Line 1. The complete cracking process, internal force redistribution, and ultimate failure modes are analyzed. Results identify a sequential failure pattern: cracks initially initiate at the invert, subsequently appear at the crown, and then interconnect at the springlines, ultimately leading to structural collapse. Pre-existing cracks are shown to significantly degrade structural stiffness and bearing capacity, with severity increasing with crack depth. Specifically, a crack depth of half the lining thickness reduces the ultimate bearing capacity by 24 %–26 % at the crown and up to 30 % at the invert. This work validates the PD method for tunnel fracture analysis and assessing the safety of tunnel linings.