INFLUENCE OF JOINT ORIENTATION ON BLAST-INDUCED FRACTURE PATTERNS IN GRANITE ROCK USING DISCRETE ELEMENT METHOD

Blasting is widely used for rock fragmentation in quarries, but the presence of geological discontinuities (joints) disrupts the process, often resulting in uneconomic muck-piles and unstable post-blast surfaces. The primary objective of this study is to observe the effect of discontinuity orientation on development of fracture pattern in rock through numerical analysis. Discrete element method (DEM) was utilized to develop one solid and four discontinuous models of rock bench with variable joint orientations, using the Bonded Particle Model for rock material and Particle Blast Method for blast loading. The joint hinders fracture development, allowing the blast energy to dissipate through void. Dominant fractures develop within 20 ms in the solid model, whereas the discontinuous model with a larger dip and dip direction (70°, 174°) does not exhibit significant cracking within this timeframe. The angle between the dip direction and the normal axis of the free face influences fracture generation mostly; when these align, the risk of slab failure and the formation of large rock fragments intensifies. Overall, DEM can be utilized to simulate the blast operation, and the findings of this research can aid in deciding the right orientation and appropriate delay time for blast operation in rock quarries.