An analytical–numerical method for the hydraulic–mechanical coupling analysis of time-dependent behavior of pressurized tunnels: Impact of an excavation damaged zone

Abstract

The issue of pressurized tunnels has been sufficiently investigated in the literature; nevertheless, the long-term behavior of the problem, which is the case in very squeezing conditions, remains unexplored. From a practical standpoint, the development of a damaged zone around the tunnel, due to the poor quality of blasting for excavation, imposes an additional challenge in predicting tunnel responses. This paper introduces an analytical approach addressing both water seepage and the excavation damaged zone (EDZ) concerning the long-term behavior of lined circular pressurized tunnels. To achieve this goal, the rheological behaviors of the initial rock mass and damaged zone are modeled using the Burgers model, along with considering the time-dependent variation in the rock mass hydraulic conductivity. After the validation of the model, the conducted parametric studies reveal that rock mass and lining hydraulic conductivities, EDZ radius, and the Burger shear modulus are the most influential parameters.