Modeling of Rheological Deformation of Inhomogeneous Rock and Associated Time-Dependent Response of Tunnels

Abstract

An exponential creep model on the basis of material properties degradation law was applied in the paper to simulate the rheological behavior of inhomogeneous rock and time-dependent response of rock tunnels. The primary, secondary, and tertiary creep regimes associated with damage were observed in the simulations, indicating that the macroscopic creep failure is linked to clusters of microstructure damage evolution at a mesoscale. Simulations on the time-dependent response of tunnels in the long-term under different coefficients of lateral pressure show that creep deformation and damage occurs in rock mass at tunnel sidewalls around rock mass under the coefficient of lateral pressure less than unity, whereas creep deformation and damage occurs at the roof and floor of the tunnel under the coefficient of lateral pressure larger than unity. Under the hydrostatic pressure of the coefficient of lateral pressure equal to unity, creep deformation and damage randomly occurs and damage localization forms and failure occurs at weak zone of the tunnel. Furthermore, tunnel closure displacements of the tunnel wall along the horizontal direction under three coefficients of lateral pressure are directly proportional to the coefficients of lateral pressure. Tunnel closure will be a maximum in the maximum principal stress direction and a minimum perpendicular to it for the coefficients of lateral pressure differing from unity.