An internal-strain loading approach for quasi-static fracturing in brittle rocks via the grain-based model

The grain-based model is used to study the time-independent and time-dependent behavior in damage evolution and fracture patterns of brittle rocks. The standard loading approach (i.e., the model is loaded by applying constant velocities at boundaries of the model based on the test procedure) is the primary loading approach for quasi-static simulation in the grain-based model, but the computational efficiency of this approach is relatively low. We developed herein the internal-strain loading approach, a more efficient loading approach, for simulating the mechanical behavior of brittle rocks. The internal-strain loading approach was embedded into the threedimensional discrete element grain-based model (3DEC-GBM). The internal-strain loading approach was compared to the standard loading approach using triaxial compression, direct tensile, and direct shear simulations. The results showed that the internal-strain loading approach was able to accurately reproduce both the deformation behavior and strength of the laboratory experiment. Compared with the standard loading approach, where the axial velocity of two plates was 0.0025 m s(-1) in the compression simulation, the internal-strain loading approach can reduce the model run times by up to ten times. We conclude that the proposed internalstrain loading approach is a powerful tool that can improve the computational efficiency of the grain-based model.