Optimal Charge Scheme Calculation for Multiring Blasting Using Modified Harries Mathematical Model

A new optimization method for optimal charge scheme calculation is proposed to reduce undesired phenomenon in ring blasting, including brow damage, overcrushing, and bulking yield, which are caused by the unreasonable distribution of blasting energy. First, all the feasible charge schemes are calculated by a traversal algorithm. Then fragment size value is predicted according to the blasting simulation program, which is based on a modified Harries mathematical model. Finally, the optimal charge scheme is selected by the X-50 and X-90 - X-10 of fragment size value of the muck pile. The program is developed by Visual LISP on the AutoCAD platform. A case study illustrates the optimization procedure, and some field tests were conducted in Tonglvshan copper mine and Fankou mine to verify the feasibility of the program. The optimization method can play a positive role in brow protection. It can also obviously improve the muck pile fragment-size distribution. (C) 2019 American Society of Civil Engineers.