Abstract
The mechanism of rock fragmentation around blastholes is of prior importance in the evaluation of drilling and blasting performance in open pit and underground mines. This paper aims to numerically investigate the crack propagation mechanism around a single blasthole using the distinct element method (DEM). In this study, two specimens with different borehole diameters were considered and the effects of the stress waves on their cracking mechanism were simulated. To validate the numerical model, the length of the radial cracks around each blasthole was measured and compared against an analytical fracture mechanics model. The fractured zones around the blasthole were also compared against previous experimental tests and good agreement was observed. The effect of a single discontinuity on the crack propagation mechanism was also studied and it was found that the discontinuity normal stiffness plays a significant role in the fractured zones around the blasthole. For low values of normal stiffness, the discontinuity surface acted as a free surface, and the shock wave was significantly reflected, while at high values of normal stiffness, cracks propagate across the discontinuity surface.
Highlights
Blasting is a common practice for rock mass breakage which is commonly used in mining and civil industries such as open-pit mines and underground tunnels
Fracturing patterns, crack length estimation, and the number of radial cracks around the blastholes are the main concern in the rock fragmentation analysis
Analytical, and numerical studies have been devoted to explore the radial crack propagation mechanism around the blastholes drilled in some typical rocks
Summary
Blasting is a common practice for rock mass breakage which is commonly used in mining and civil industries such as open-pit mines and underground tunnels. This paper aims to investigate the effect of a blastinduced stress wave on rock fragmentation in intact rock and jointed rock mass To this end, two different cylindrical samples with a central borehole were numerically simulated using a universal distinct element code (UDEC) and the results were compared against physical experiments undertaken by Dehghan Banadaki (2012). Using the validated numerical models, the effects of mechanical and geometrical properties of single discontinuity on rock fragmentation and the fracturing pattern were investigated. The LEFM theory has been effectively employed in dynamic rock fracture mechanics as well as the crack branching process, which occurs in some dynamic phenomena such as rock blasting and rock fragmentation by disc cutters (Bažant, 1984; Feng, 2017; Irwin, 1957). Where: a – the length of a radial crack having n arms, R – the radius of blasthole
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
