Based on cusp-type catastrophe theory, a sample rock-rock (hypocenter surrounding the rock) model for studying the pillar rockburst mechanism is presented in this paper. It is expounded theoretically that the stiffness ratio, K, of the roof and floor to the pillar plays an important role in the outbreak of instability. Using a newly developed numerical code, RFPA2D, the progressive failure process and associated microseismic behavior of the twin rock samples are simulated. The numerically simulated results also confirm that a soft roof and floor promotes an unstable failure or collapse of pillars. Additionally, the simulated results reproduced the deformation jump and the energy release that occur during a pillar rockburst. It is demonstrated that the proposed model properly simulates the pillar failure process.