A modified particle contact model for matching the ratios of uniaxial compressive to tensile strength of brittle rocks

The Hertz-Mindlin with bonding (HMB) contact model in the commercial discrete element method (DEM) software EDEM is widely used to simulate and analyze the mechanical behavior of rocks. However, it cannot match the high ratios of uniaxial compressive strength (UCS) to tensile strength (TS) observed in brittle rocks like basalt. In this study, a modified HMB contact model was developed by adequately considering the contribution of moment to stress and the influence of normal stress on shear strength. At the same time, a DEM parameters inversion method was proposed to achieve rapid and accurate calibration of various microscopic parameters. The results indicate that the moment-contribution factor and maximum tensile strength in the modified HMB contact model are two key parameters affecting the UCS/TS ratio. Specifically, the moment-contribution factor mainly affects UCS, while also jointly influencing TS together with the maximum tensile strength. The modified HMB contact model successfully achieves the high UCS/TS ratio that aligns with the test value and exhibits significant pressure-dependence. This model proves to be appropriate for accurately simulating the mechanical behavior of brittle rocks.