Three-Dimensional Seepage Investigation of Riverside Tunnel Construction Considering Heterogeneous Permeability

Seepage is a major concern during the construction of a riverside tunnel, because the seepage may cause both hydraulic and mechanical problems. At present, there are some well-accepted methods combining the hydraulic-mechanical coupling effect. This paper investigated a tunnel near a riverside under seepage forces using hydraulic-mechanical coupling analysis. Two cases were considered: an unlined tunnel without waterproofing, and a tunnel with a cement-treated soil surround acting as water barrier. The spatial variability of hydraulic conductivity was taken into account using random finite-element analysis. Results indicated that the analysis is able to account reasonably for the variation range of soil parameters. The arithmetic mean of hydraulic conductivity could serve as a rule of thumb estimation for a macroscale representative hydraulic conductivity. The results are likely to yield a scientific estimation of the seepage flow as well as a better understanding of the potential tunnel collapse mechanism. (c) 2021 American Society of Civil Engineers.