Stability of the overworked slightly metamorphosed massif around mine working

Abstract

The study of mechanisms of the overworked slightly metamorphosed massif stability around mine working using the example of laminal rocks in the Western Donbas (Ukraine). Methods. The analysis of the overworking influence when planning mining operations on the underlying horizons has been made based on the studies of the stress-strain state on the overlying horizons. Attention was paid to the conditions of a slightly metamorphosed coal-bearing rock massif, which has specific mechanical properties and structural peculiarities. A computational experiment by the finite element method has been performed. The model adequacy and the calculation accuracy of the stress-strain state have been proved. The research results have been confirmed by a mine experiment. Findings. The geomechanical model of the computational experiment has been substantiated, in which the real massif structure, factors of stratification, fracturing, and moisture saturation, which weaken the strength and deformation properties of the rocks, are reflected. The zones of uncontrolled collapse, hinged-block displacement, and smooth deflection of layers without discontinuity have been studied. Originality. The patterns of the overworking influence on the state of mine workings in the laminal massif of soft rocks have been determined. Therewith, three areas of lithotypes discontinuity throughout a height of a parting have been identified and the stresses components parameters, as well as their compliance with real mining and geological conditions have been analysed. Practical implications. It has been proved the absence of the overworking influence on the underlying mine workings state in a slightly metamorphosed massif. A comparative analysis with the mine experiment results has been made. The possibility of mining the protecting pillar reserves is shown, which will allow to extract additional coal without attracting significant material resources.

Optimization of Energy Efficiency of a Heat Recuperator on the Basis of Underground Coal Gasification

“…The same situation is observed within the burned-out space. Along with the coal seam gasification and fire face advance (7), roof rocks (27) are collapsing under the effect of rock pressure and rock temperatures with the formation of a burned-out space of the gas generator. Heat and gasification products leave the gas generator through the well (4) and vertical gas outlet well (9); and a heat share (up to 30-49 %) is accumulated within the rocks enclosing the gas generator (see Fig.…”

“…If such method is implemented, one should select the mines with a completed operating period and with substandard, overworked or underworked reserves of solid fuel [6,7]. The underground gas generator is prepared under the mine conditions with drilling of a stowing well in the seam roof, horizontal production wells throughout the seam, linkage between them, seam ignition, blow supply, coal gasification, syngas obtaining, and stowing of the deformed roof rocks and burned-out space [8][9][10][11].…”

Prospects of using the polymetallic ore processing waist for producing hardening mixtures

“…An analysis of work to maintain underground excavations under complicated mining and geological conditions [19,20] showed that shotcrete is an eff ective method for ensuring stability. High technological and technical and economic indicators of lined roadways are achieved due to the correctly selected composition of the concrete mix for shotcrete, taking into account the specifi cs of underground operations.…”

Substantiating the parameters for selecting a pillar width to protect permanent mine workings at great depths

“…-protection with large pillars [1,2]; -preliminary and following overworking of mine workings [3,4], -arrangement and support of mine workings within the caved and consolidated rock thickness [5]; -protection of mine workings by gob packs within the regional de-stressed zone [6].…”