Micromechanical modeling of time-dependent deformation and delayed failure in tunnels

A micromechanical model based on material properties degradation law was proposed in the paper to simulate the time-dependent damage and deformation and delayed failure of rock materials in tunnels. The time-dependent degradation law of material properties, an exponential empirical relation between degradation of material properties and applied stress, is used at the scale of each element to simulate its damage. The primary and tertiary creep regimes associated respectively with a degradation and increase of the rate of strain, damage event and energy release were observed in the simulations. The time-dependent deformation and delayed failure of tunnels on the long-term under different coefficients of lateral pressure was studied to investigate the failure patterns and mechanism of tunnels. This model can reproduce rheological properties including the three creep regimes and associated damage evolution of rock in tunnels, which is of great help to investigate long-term stability of tunnels and to prevent associated rock hazards in tunneling engineering.