A short overview of the research program of SveBeFo, Swedish Rock
Engineering Research, which was founded in 1993 is first given. Then
four recent and ongoing projects in rock blasting and explosives
engineering are presented in greater detail: 1. Burn Equations for Commercial Explosives.
2. Blast Damage in Contour Blasting. 3. The Role of Gas Pressure in Pit Wall Damage. 4. Fragmentation of Aggregate Rock. The goal of the bum equation project is to be able to control the energy
release from explosive charges to the desired part of the expansion curve
of the reaction products under various rock conditions. SveBeFo's work
has reached the stage where a burn equation for a lab emulsion has been
established which can model the influence of charge diameter on the
VOD and detonation front curvature in a cylindrical charge quite well.
This work now continues with other emulsion recipes. In the blast damage project the goal is to develop techniques and
recommendations on how to minimise the blast damage in construction
blasting. The project has gained extensive practical knowledge from the
blasting of more than 200 holes in a granite quarry under controlled
conditions. The cracks in the rock surrounding the contour holes have
been cut open and measured. The influence of factors like charge
concentration, decoupling ratio, hole and charge size, VOD and time
delay in initiation have been investigated. A simultaneous initiation of a
group of contour holes with EDD detonators is quite superior to single
hole blasts, even when they are timed as closely as 1 ms.