Analytical solutions for lined noncircular tunnels in deep ground considering hydromechanical coupling

Abstract This study provides a general analytical approach to predict the stresses and displacements of deep noncircular tunnels excavated in saturated elastic ground, considering the hydro-mechanical coupling, the interaction between rock and liner, and arbitrary tunnel shapes. The complex variable theory is innovatively extended to solve the seepage fields for noncircular supported tunnels in both surrounding rocks and liner fields. After that, coupled hydro-mechanical solutions of stresses and displacements can be determined by considering the influence of seepage flow on the mechanical responses. Furthermore, stability analyses of supported tunnels are conducted in the hydro-mechanical coupled framework, incorporating the effect of seepage flow. As a verification, a good agreement is observed between stress and displacement fields obtained from the current analytical solutions and numerical simulations. Then, parametric analyses are performed to assess how variations in tunnel shape, liner permeability, and liner thickness influence the mechanical behaviours of supported tunnels. Meanwhile, by employing the Mohr–Coulomb strength criterion, an expression of equivalent stress is proposed to assess the potential failure behaviour of supported tunnels in the entire process of excavation and operation stages. This study provides high potential of application to a number of relevant case studies, such as tunnelling below the water table.