Determination of the radius of the zone of explosive loosening of a fractured rock mass when blasting a borehole charge

• Main Authors: O.O. Frolov, M.I. Beltek
• Format: Article
• Language: English
• Published: Zhytomyr Polytechnic State University 2020-12-01
• Series: Технічна інженерія
• Subjects: explosion; zone of explosive loosening; intensive crushing; mountain range; fracturing; radius of the crack formation zone
• Online Access: http://ten.ztu.edu.ua/article/view/217625/217536

The work presents the results of scientific research on determining the radius of the zone of explosive loosening of fractured rock massifs during the explosion of a borehole charge of an explosive in it. It has been established that the parameters of the explosive loosening zone depend on the size of the zones of intense crushing and cracking, which are formed under the action of an explosion in a monolithic rock mass and depend on the diameter of the charge, the charge density and the detonation rate of the explosive, and the compressive and shear strength of rocks. An analytical dependence is obtained for determining the radius of the zone of explosive loosening in fractured massifs, which connects the main characteristics of the rock mass and the explosive charge. It is proved that the radius of the zone of explosive loosening increases, in comparison with the radius of the zone of cracking in a monolithic massif, inversely proportional to the coefficient of structural weakening, which in turn depends on the average distance between cracks. For mining, geological and technological conditions of an iron ore opencast, the values of the radius of the zone of explosive loosening are calculated depending on the distance between natural cracks in the rock mass. It has been found that when the distance between cracks changes from 0,1 to 2,0 m, the value of the radius of the loosening zone decreases from 6,24 to 3,09 m, that is, 2,01 times. At the same time, the greatest intensity of its decrease falls on the massif of the second category of fracturing, and the numerical value decreases by 1,65 times with an increase in the distance between the cracks from 0,1 to 0,5 m. The results obtained make it possible for any mining-geological and technological conditions of a career to design rational parameters of drilling and blasting operations, which are based on taking into account the radius of the zone of explosive loosening of a rock mass during the explosion of borehole charges in it.