Physical and simulation modelling of solid media fracturing by means of explosive charges of different cross-sectional shapes

Abstract

Purpose is to evaluate experimentally and theoretically a mechanism of solid media fracturing by means of explosive charges varying in their cross-sectional shapes. Methods. The Mohr-Coulomb strength condition has been applied to describe rock transition to the disturbed state. The condition has become a basis to develop a mathematical model of explosion (i.e. shock and detonation wave) of the concentrated borehole charges. The simulation explosion was modelled while adequate load applying at the points belonging to the outline of both cylindrical charge and at the charging angles in the shapes of triangular and square prisms. The evaluation mechanism of solid media fracturing by means of explosive charges, varying in their shapes, used the models made of optically active materials. A method of high-speed photorecording of the process was involved; the method was combined with the photoelastic technique of stress analysis. Findings. Taking into consideration rock transition to the disturbed state, the Mohr-Coulomb strength condition was applied with the possibility to simulate failures resulting from shear as well as from separation according to the developed mathematical model. The calculation results have helped identify distribution of a geomechanical parameter (Q) at different time points (time iterations). Dependencies of changes in the maximum component of the main stress tensor σ1 / γН along the axis passing through the charge centres perpendicularly to its flat surface for different time iterations have been developed. It has been defined that the maximal stresses are concentrated on the top of both triangular and square prisms helping shape a denser crack network within the zones. Originality. It has been identified that at the initial explosion stage, the maximum values of the main stress tensor component σ1 / γН along the axis passing through the charge centre perpendicularly to its flat surface, experience certain change depending upon a power law with the increasing distance to the charge outline. At the same time, if the charge is of a square prism shape then time iteration being i = 5 makes the main stress decrease according to a linear dependence. Practical implications. The research may be used as the basis for the development of rational parameters of the resource-saving methods applied to separate hard complex rocks in terms of open pits where building materials are mined.

Determining the Performance of Explosives for Blasting Management

“…As for a value of performance index of the explosives calculated according to the proposed methodology, its magnitude considers the main explosive characteristics: heat and volume of the explosion products, density, and detonation velocity. Considering a performance index of explosives while calculating and designing the IE parameters helps achieve more accurate results (Fedko et al, 2019;Ishchenko, 2022).…”

Investigation of the Process of Destruction of a Roain Massif by Borehole Charges with an Axial Air Cavity by the Method of Physical Simulation

“…The blasting of wells in a row is instantaneous, between the rows it is short-delayed. Since short-delayed blasting on models with the help of industrial short-delayed electric detonators is impossible, a scheme of automatic short-delayed blasting of charges using shunts was used [19][20][21][22][23][24]. The designs of the charges are shown in fig.…”

Optimization Study of Water Interval Charge Structure Based on the Evaluation of Rock Damage Effect in Smooth Blasting

“…In the above study, the optimization of the water interval charge structure is based on the standard of safe blasting velocity or rock damage range. Damage to the rock under blasting loads is adjusted by Mises' damage criterion or the Mohr-Coulomb strength condition [12,13]. It has been concluded that crushed zones were formed closer to the source of the explosion, while fissure zones were formed slightly further away under compressive and tensile stresses, respectively.…”