Numerical simulations of rock blasting damage based on laboratory-scale experiments

In order to study the damage induced by rock blasting, a numerical simulation method based on the Johnson-Holmquist II (JH-2) damage model combined with the arbitrary Lagrangian-Eulerian (ALE) method is proposed. The process of dynamic breakage and damage evolution of Barre granite is reproduced using explicit hydrocode, ANSYS/LS-DYNA, based on the prototype experiments in the laboratory. The results show that both the crack patterns and measured pressures are in agreement with the results from the lab-scale experiments. The attenuation curves of the pressure and particle peak velocity (PPV) along the radial direction are respectively determined, and the corresponding theoretical formulas are summarized together with the most suitable attenuation exponent alpha. In addition, comparisons of blasting tests separately carried out using the discrete element method-smoothed particle hydrodynamics hybrid method and the ALE/JH-2 method demonstrate similar crack patterns formed both in intact rock disks and jointed rock disks. In the jointed rock disk, the pressure sharply declines when crossing the joint surface, while the PPV close to the joint increases before going across the joint surface, representing the 'weak transmission-strong reflection' effect of the joint surface. Different yield stresses of joint properties are farther studied, which indicate that joints with a lower magnitude of yield stress can prevent more transmissions of waves crossing the joint surface. In future studies, the ALE method combined with the JH-2 damage model can be applied to larger-scale rock engineering problems to optimize the blasting design.