Stress Evolution and Spatial Effect of NPR Anchor Cable Support in Super-Large-Span Tunnel Excavation: Insights from Model Tests and Numerical Simulations
摘要
The excavation area of the super-large-span tunnel at the junction of Qiaocheng East Road right-line section in Shenzhen is 470.5 m2, and the construction process faces involves significant risks. The stress evolution and spatial effects of the surrounding rock in super-large-span tunnels are not yet fully understood. Therefore, this study integrates field investigations, geo-mechanical model tests, and numerical simulations to examine the stress evolution of the surrounding rock and axial force of the negative Poisson’s ratio (NPR) anchor cable support under the reserved core soil excavation method in super-large-span tunnels. In addition, the longitudinal and transverse advance and lag disturbance zones of the surrounding rock at various tunnel positions are quantitatively analyzed. The results reveal that the coupling compensation support mechanism of NPR anchor cables and surrounding rock is characterized by: increasing the radial stress of the surrounding rock at the tunnel face while effectively reducing the peak of tangential stress concentration; and enhancing the transverse arching effect through the superposition of NPR long and short anchor cables, significantly reducing the disturbance range of the shallow surrounding rock in the tunnel. This study provides significant insights for the design and construction of super-large-span tunnels.