Blasted Rock Mass Research Articles

Fragmentation prediction using improved engineering formulae

In the last decade, fragmentation prediction has been attempted by many researchers in the field of blasting. Kuznetsov developed an equation for the estimation of average fragment size, x 50, based on explosive energy and powder factors. Cunningham introduced a uniformity index n as a function of drilling accuracy, blast geometry and a rock factor A associated with a “blastability index”, which can be calculated from the jointing, density and hardness of the blasted rock mass. Knowing the mean size and the uniformity index, a Rosin-Rammler distribution equation can then be derived for calculating the fragment size distribution in a blasted muckpile. Analysis of existing data has revealed serious discrepancies between actual and calculated uniformity indices. The current integrated approach combines the Kuznetsov or similar equation and a comminution concept like the Bond Index equation to enable the estimation of both the 50% and 80% passing sizes (k 50 and k 80). By substituting these two passing sizes into the Rosin-Rammler equation, the characteristic size x c and the uniformity index n can be obtained to allow the calculation of various fragment sizes in a given blast. The effectiveness of this new fragmentation prediction approach has been tested using sieved data from small-scale bench blasts, available in the literature. This paper will cover all tested results and a discussion on the discrepancy between measurement and prediction due to possible energy loss during blasting.

In-situ shear testing of blasted rock mass associated with a slope stability analysis : Ozgenoglu, A Proc International Conference on Mechanics of Jointed and Faulted Rock, Vienna, 18–20 April 1990P365–370. Publ Rotterdam: A A Balkema, 1990

In-situ shear testing of blasted rock mass associated with a slope stability analysis : Ozgenoglu, A Proc International Conference on Mechanics of Jointed and Faulted Rock, Vienna, 18–20 April 1990P365–370. Publ Rotterdam: A A Balkema, 1990

Relative strength characteristics of fragments of a blasted rock mass and the blocks of a rock mass

Relative strength characteristics of fragments of a blasted rock mass and the blocks of a rock mass

Increase in the efficiency of using explosive energy for deep-hole charges under conditions of flooded rock masses

The charge mass of water-resistant explosives necessary to form a water spacer is determined by means of a nonogram. It takes account of flooding for blast-holes, jointing of the rock mass, and type of explosive substance used. Analysis of seismograms obtained with explosion of blast-hole solid charges and dispersed charges has shown that a reduction in seismicity in the second case occurs not only as a result of the normal reduction in charge mass, correspoinding to he volume of the water spacer cavity, but also as a result of the positive role of the water spacer itself. The overall savings obtained on introducing deep-hole charges with water spacers is 0.06 ruble/m/sup 3/ for blasted rock mass.