Modeling of viscous behavior of rocks for deep tunnels

Lemaitre viscoplastic law, as a suitable viscous model for deep underground openings is developed in this paper. This model is implemented in a finite difference code for use in research and engineering projects. Different laboratory testing paths for the determination of viscous media parameters, applied for a sandstone and a shale, are given. Since experimental duration is material and path dependent, we are discussing how specimen-testing time, during primary creep can be shortened with no more information loss. This theoretical model was applied to simulate a deep circular tunnel. Stress relaxation at the tunnel wall was highlighted as well as time dependent gallery closure. It is intended to achieve the code implementation, by taking into account the secondary creep behavior, to compare monitoring data of existing tunnels, as a back computational analysis for validation of such model.