Blasting is the most common method used to fragment rock in the mining industry. However, given the violent nature of explosives and the high variability of results that can occur from blast to blast, there is potential to cause significant damage to the final walls of an open pit, which can lead to slope stability problems, catch bench filling, long-term rock fall hazards and ramp closure. Blasts need to be designed to suit the characteristics of the rock to be broken. Characteristics of the existing rock mass such as natural jointing, joint orientation, joint condition, and the strength of the rock, all need to be accounted for prior to designing a blast.
In general, blasting engineers rely on a combination of empirical analysis and rules of thumb for blast designs. The uncertainty involved with these techniques can lead to significant problems in open pit mining. At the bench scale of an open pit mine, the loss of the bench crest is a concern, however at the full pit scale, bench deterioration can jeopardize worker safety and lead to potential closure of the mine. The results of a blast can be highly variable – a blast design that yields favorable results on one side of a pit can have detrimental effects on another wall of the pit or at different elevations in the pit, based on the characteristics of the rock. It often takes multiple iterations of blast designs to achieve an optimal result, which is costly and time consuming for the company that operates the mine.
The purpose of this thesis is to evaluate the effectiveness of a relatively new software package, Blo-Up, that combines both a finite difference continuum code and a distinct element code in order to model the entire blasting process from start to finish. The main focus of the research will be to examine blast induced damage sustained to final pit walls and provide techniques for minimizing damage. The specific areas of the study are:
The main findings of the research are as follows: