DETERMINATION OF HOLMQUIST-JOHNSON-COOK CONSITIUTIVE MODEL PARAMETERS OF ROCK

The Holmquist-Johnson-Cook (HJC) model is a computational model for describing the dynamic constitutive behaviours of concrete. In this paper, the HJC model was extended to describe the dynamic behaviours of rock. In order to rationally determine the parameters of HJC rock constitutive model, the relationship between the cohesion parameter and the cap model parameters was derived firstly based on the plastic yield surface theory. Secondly, the strength, pressure and strain rate constants were obtained based on the tri-axial compression test, the Hugoniot experiment, and the Hopkinson pressure bar experiment. Thirdly, the projectile penetration tests on Salem limestone targets were numerically simulated by using finite element program LS-DYNA, and the obtained parameters values were verified by comparison between the depth of penetration obtained from experiments and numerical simulations. Furthermore, the sensitivities of 19 parameters related with the HJC model were discussed, and the approach for acquiring HJC model parameters of general rocks was recommended. The proposed method was verified by comparing the penetration depth between the simulation results and the projectile penetration tests on high strength granite and Sidewinder tuff.