Fragmentation Energy in Rock Blasting

Abstract

The theoretical explosive energy used in blasting is a common issue in many recent research works (Spathis 1999; Sanchidrian 2003). It is currently admitted that the theoretical available energy of the explosives is split into several parts during a blast: seismic, kinetic, backbreaks, heave, heat and fragmentation energies. Concerning this last one, the energy devoted to the breakage and to the creation of blocks within the muckpile can be separated from the microcracking energy which is devoted to developing new and/or extending existing micro cracks within the blocks (Hamdi et al. 2001;López et al. 2002). In order to investigate these two types of energy, a first and important task is to precisely study the main parameters characterising the two constitutive elements of the rock mass (rock matrix and discontinuity system). This should provide useful guidelines for the choice of the blasting parameters (type of explosive, blasting pattern, etc.), in order to finally control the comminution process. Within the frame of the EU LESS FINES research project, devoted to the control of fines production, the methodology was developed in order to: (1) characterize the in situ rock mass, by evaluating the density, anisotropy, interconnectivity and fractal dimension of the discontinuity system and (2) evaluate fragmentation (both micro and macro) energy spent during the blasting operation. The methodology was applied to three production blasts performed in the Klinthagen quarry (Sweden) allowing to estimate the part of the fragmentation energy devoted to the formation of muck pile blocks on one side and to the muckpile blocks microcracking on the other side.

Detection of quarry and mine blast contamination in European regional catalogues

“…Explosives are the primary source of energy for rock breaking in the mining, quarrying and construction industries (Sanchidrián et al 2007: Hamdi et al 2008; they are also employed in salt, coal and ore mining, to excavate underground mines and in civil engineering (e.g. tunnel and subway).…”

“…Explosives are the primary source of energy for rock breaking in the mining, quarrying and construction industries (Sanchidrián et al 2007;Hamdi et al 2008), particularly for limestone, gypsum, conglomerates, building materials and, in general, to obtain rock fragmentation. Explosives are also employed to excavate underground mines and blasting is the usual method for ore mining: for example the gold extraction, performed by creating huge excavations-using 150 kg of dynamite per day in Romania (http://terraii.ngo.ro; http://www.rosiamontana.org) and processing the metals with cyanide compounds.…”

Experimental Study of Bilinear Initiating System Based on Hard Rock Pile Blasting

“…For the bilinear initiating system is larger than that by the detonator initiating system. The principle of conservation of energy [32] states that the higher the amount of energy used to produce cracks, the better the rock breakage. Otherwise, fluid-solid coupling algorithm in the LS-DYNA…”

A tensile damage model for rocks: Application to blast induced damage assessment

“…Afterwards, the methodology was developed by using image analysis technique integrated in the commercial software Paintshop [10].…”