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The authors put forward a look-ahead concept of science-based problem solving in deep-level mining. The issues of the problem realization and tooling are also addressed. A borehole charge is designed as a cluster of close-spaced borehole charges to produce the directed blast effect by varying the cluster charge layout in a wide range. Using alternative technical capabilities of drilling, it is possible to variously redisperse the same equivalent energy in the single large-diameter borehole charge and in the cluster of smaller diameter borehole charges. The blast mechanism of the cluster charge pushes the limits of its application range and offers new approaches to problem solving in deep-level mining. Some technological aspects of geotechnologies are presented through the results of modeling the new approach to blast-induced impact using smooth particle hydrodynamics. Some tentative research findings inspire continuing with the study. [ABSTRACT FROM AUTHOR]

The fracture of brittle specimens with an initial crack under uniaxial compression is studied experimentally. The effect of the crack orientation on the fracture of the specimens is examined. It is established that the crack nucleates and advances mainly in the loading direction (longitudinal fracture being predominant). The brittle material is modeled taking into account the difference between the compressive and tensile strengths of the material, the accumulation of damage, and the degradation of strength. The results obtained with the model in analyzing the fracture of brittle specimens with an initial crack under uniaxial compression are in satisfactory agreement with experimental data [ABSTRACT FROM AUTHOR]

Modern conditions of mineral deposit development are characterized by more stringent requirements as to the environmental impacts of production and the increased volume of blasting operations near populated areas. The importance of the study is due to the need of developing energy-efficient technologies for crushing rocks, finding safe ways to intensify the coal degassing processes and reducing the intensity of methane inflow into the mined-out space. The Smoothed Particle Hydrodynamics numerical method used in this work allows adequately calculating nonlinear dynamic problems arising during blasting development of mineral deposits, while the use of most other computer modeling methods to solve these problems causes significant computational difficulties. The paper presents the results of a study of the nature of variations in the rock displacement velocity and the stresses and parameters of the radial crack propagation zone from the distance to the charge during blasting operations in monolithic and fractured massifs. [ABSTRACT FROM AUTHOR]