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Evaluation of blast wave parameters within the near-explosion zone in the process of rock breaking with borehole charges

2020; Issue: 2 Linguagem: Inglês

10.33271/nvngu/2020-2/047

2223-2362

В.В. Соболев, Вячеслав Кулівар, O.L. Kyrychenko, Anton Kurliak, О.O. Balakin,

Rock Mechanics and Modeling

EVAluATIon of BlAST wAVE PArAMETErS wIThIn ThE nEAr-EXPloSIon ZonE In ThE ProCESS of roCK BrEAKInG wITh BorEholE ChArGESPurpose.To analyse the experimental results, to describe physical mechanism of blasted rock disintegration and develop meth odology to calculate blastwave parameters within the nearexplosion zone, and to study possible role of thermoelastic stresses in rock fragmentation to ultradisperse fractions in the nearexplosion zone.Methodology.The experiments involved a method to measure dynamic compressibility of bituminous coals based on the de termination of both velocity of blast waves and mass velocity of particles beyond the front.A reflection method is used to construct isentropes of the explosive detonation products and their impact adiabat.findings.Experimental studies are carried out to analyse compressibility parameters of bituminous coals -blast wave velocity and mass velocity of particles beyond the blast wave front.Impact adiabats for emulsion explosive ЕРА Р3 and bituminous coals are constructed.A set of theoretical studies is performed.originality.Methodology to evaluate blastwave parameters within the zone near the borehole or blasthole charge explosion is proposed.Physical mechanism for rock breaking to ultradisperse particles is proposed.It has been specified that thermoelastic stresses may be one of the possible causes, if not the main one, of the rock breaking within the nearexplosion zone.A mechanism stipulated by the transition of microstructure of the rock crystalline components to the instable state is considered as the alternative (or additional) factor.The cause is in the oversaturation of the rock microstructure with the linear and point defects.Exceeded value of critical concentration of those defects results in the excessive reserves of internal energy with the following spontaneous breaking of chemical bonds.Impact adiabats of coking coals of three grades as well as isentrope and impact adiabat of the detona tion products of emulsion explosive ЕРА Р3 are constructed.In terms of the "pressure -mass velocity of particles" coordinates, curves of adiabats of the bituminous coals differ by not more than 4 %.Practical value.Analysis of the scientific results may be the required condition to develop additional safety measures in the sphere of environmental protection during blasting operations in terms of openpit and underground mining.