Study about influence of RC segment degradation on seismic response of shield tunnel

The seismic performance of shield tunnels is significantly influenced by material deterioration, particularly under aging and environmental stresses. This study investigates the impact of reinforced concrete (RC) segment deterioration on the seismic response of shield tunnels using a three-dimensional finite element model. A comprehensive deterioration factor is proposed based on the Concrete Damage Plasticity (CDP) model, simultaneously accounting for the degradation of stiffness and strength to characterize the deterioration of concrete segments of shield tunnel. The accuracy of the deterioration factor was validated through experimental data on degraded concrete specimens. Subsequently, numerical simulations were conducted for tunnel deterioration levels ranging from 0 % to 30 %, analyzing key parameters including deformation, internal forces, energy distribution, and plastic damage. Results indicate that as deterioration intensifies, tunnel deformation increases, with vertical and lateral displacements rising by 12.5 % and 3.14 %, respectively, while the ellipticity deformation index increases by 11 %. Internal forces, particularly the bending moment at the arch waist, decrease by up to 29.42 %. The redistribution of seismic energy leads to concentrated damage in structurally weaker regions, such as the arch waist. Additionally, tensile damage increases by 7.9 times, significantly compromising structural integrity. This study underscores the interplay between aging-induced deterioration and seismic loading, offering valuable insights for optimizing seismic design, retrofitting, and maintenance strategies.