Investigation of the Effect of Discontinuities on Blast Damage Factor in the Hoek-Brown Failure Criterion for Rock Slope using 3D Discrete Element Modeling

Blast damage on the stability of the slopes plays an important role in the profitability and safety of mines. Determination of this damage is also revealed in the widely used Hoek-Brown failure criterion. Of course, this damage is used as a moderating factor in this failure criterion, and its accurate determination is considered an important challenge in rock engineering. This study aims to investigate the effect of geological structures in blast damage factor using 3D discrete element modeling of two slopes with different directions of geological discontinuities. The dynamic pressure of the explosion is also simulated in three blastholes. To ensure the modeling results, other dynamic properties of the model have been selected based on the proven studies. An analytical analysis was conducted based on the failure zones (blast damage area), and quantitative and qualitative analyses were performed using the recorded PPV values during the blasting simulation. The results show that the geological discontinuities control, damp, and reduce blast damage. The expansion of blast damage is reduced by 75% along with the increase in rock mass strength, and the blast damage can expand up to 33 meters along with the decrease in strength. By reducing the distance of discontinuities, the role of discontinuities in damping becomes greater than other properties of the rock mass and the discontinuities further away from the blasting hole create more damping. The relation between the distance from the Hole and PPV values shows that for more realistic slope stability analysis results, the values ​​of the damage factor in the Hoek-Brown failure criterion should be applied gradually and decreasingly in layers parallel to the slope surface.