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FORMATION PECULIARITIES OF CAVING ZONES AS AERODYNAMIC ACTIVE BRANCHES OF MINE VENTILATION SYSTEMS IN PILLAR MINING OF COAL BEDS

Abstract

This paper considers the formation peculiarities of caving zones depending on specific mining, geological and technical conditions. The properties of rocks representing structures complicated by man-induced and naturally occurred cracks have been analyzed. When mined-out spaces are formed, the rock massif transforms into caving zones having other properties and characteristics differing from the initial ones and affecting the filtration processes. In mining conditions, such mined-out spaces represent a fractured and porous medium of various structures (irregular or partially regular) permeable for the motion of gas and air masses. This fractured and porous medium represents an aggregate of solid bodies of various shapes and sizes adjacent to each other with the space between them (large channels and fractures), internal voids and pores filled with air and gas masses moving in the direction as established by the head gradient. The minedout spaces are considered as active branches of mine ventilation systems where air leaks are moving. A participant in gas exchange with mine workings is the so called active zone from which the air and gas mix can be fed to the working zone of the working area and affect the gas environment in workings. The size of this zone is determined by the development system and geomechanical parameters of undermined rocks that condition the caving increment of the immediate and main roof, the width and height of the caving arch, and the distance from the longwall to the beginning of the bearing pressure zone. To quantitatively assess possible leaks and gas content of working zones in case of emergency related to gas emissions from mined-out spaces, the methodology to determine the active zone volume has been developed and described in this paper. The permeability values of caving zone layers calculated with the obtained results allow identifying the consistent patterns of leak formation processes in the mined-out space.

VALERII VITALIEVICH SMIRNIAKOV AND VICTORIA VLADIMIROVNA SMIRNIAKOVA

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