Hydromechanical postclosure behavior of a deep tunnel taking into account a simplified life cycle

This paper addresses the hydromechanical postclosure behavior of an underground long cylindrical deep tunnel drilled into a massif (host medium) and backfilled at the end of its service life. It is concerned with the development of quasi-analytical Laplace transform solutions based on a simplified life cycle of the tunnel, idealized in four stages: (1) excavation, (2) pore-pressure dissipation before lining installation, (3) lining installation and tunnel exploitation, and (4) postclosure. The solutions proposed in this paper therefore extend the previous work of the authors, in this case by explicitly taking into consideration the excavation, waiting for lining installation, and tunnel exploitation stages of the life cycle. Results from a parametric study are also presented to highlight the hydromechanical responses of the tunnel over periods of its life cycle. The accuracy and correctness of the solutions from a finite-element model have been verified with the quasi-analytical results. The present solutions will be used later for benchmarking finite-element-based solutions currently under development, taking into account more complex material behaviors.