Abstract
There seem to be three types of failures as essential factors when rock is blasted. We have conducted observation of the actual bench and coyote blasting in the field in order to study the differences of blasting effect caused by these types of explosives and drilling patterns.
These three types of failures take place almost at the same time. Generally speaking, however, only one out of these three appears prominently on most occasions.
In other words, it has been observed quite often that shear type failure causes the highest percentage of blasting action. Accordingly, when bench blasting is designed, it is recommended in most cases to keep the hole as deep as possible in the field circumstances. Thus, it is expected that the lower part of the bench is to be blasted by the shock effect and the upper part by the sliding effect.
There remains slight difference in the charged volume, however, due to the particular circumstances of the field. In general, the conventional application of Livingston formulae can be recommended in most cases.
