Numerical Simulation of Rock Creep Behavior with a Damage-Based Constitutive Law.

Time-dependent creep behavior of rocks is crucial not only for assessing geophysical hazards, such as earthquake rupture and volcanic eruption, but also for analyzing the long-term stability of rock engineering structures, such as underground mines and underground excavations. In the present paper, multiple stress-stepping creep tests on green sandstone under uniaxial stress conditions were performed. Results from stress-stepping creep experiments show that creep strain rates are highly dependent on the level of applied stress. Then, a time-dependent creep model based on damage constitutive law at a mesoscale was proposed to model the time-dependent behavior of heterogeneous brittle rocks. In the proposed model, the rock heterogeneity is considered by assuming the rock parameters following a statistical Weibull distribution, and both the maximum tensile strain criterion and the Mohr-Coulomb criterion are used as two damage thresholds to control the rock damage. The damage-based creep model is implemented by programming on the basis of finite-element software. Then the model was validated by comparing the numerical simulations with the experimental results. The model accurately captures the time-dependent creep behavior observed in the laboratory. It was then used to simulate the time-dependent evolution of damaged zone around an opening under different lateral pressure coefficients. The distribution of damage around the opening is realistically reproduced, and the simulations indicated that the spatial distribution of damage zones, as well as time to failure, is closely related to the lateral pressure coefficient. [ABSTRACT FROM AUTHOR]