Numerical study of cracking process using a new contact model

In this paper, the three dimensional Particle Flow Code (PFC3D) with a newly developed contact model which can properly consider the contribution of moment to contact normal and shear stresses and the condition at which the contact bond fails was used to investigate the cracking process of rocks containing single flaws and under uniaxial compression. The new contact model was first validated by using it to simulate the experimental cracking process of gypsum containing pre-existing single flaws at different inclination angles. Then the influence of flaw shape (length and thickness) on the cracking process was systematically studied and the key features were identified based on the simulations. The results indicate that the first cracks (usually called primary cracks) initiate from the boundary of the pre-existing flaw and are always caused by tensile failure, and the secondary cracks first emanate from the tips of the pre-existing flaw due to shear failure and then develop to a mixed shear and tensile cracking zone.