Determining the parameters of stratification cavity in rock mass to extract mine methane

Purpose. Substantiation of the stress-strain parameters of a rock mass state to identify potential mine methane accumulation in the roof rocks of the extraction pillar. Methodology. Characterization of stratification cavity in rock mass for mine methane extraction relied upon analytical studies. The research is based on a method by Professor O.V. Savostyanov to calculate a stress-strain state of rocks. The method has been implemented in GeoDenamics Lite software. The use of the method helps obtain both geometrical and physical parameters of load characteristics for typical rock layers from the coal seam up to the surface. The abovementioned makes it possible to identify areas of rock stratification, coal bench being flaked away, and the number of rock layers after stratification. Mining and geological conditions of the coal seam occurrence and mining technology are the output data for the research. Findings. Analysis of geometrical and physical parameters of load characteristics on the roof rocks of a coal seam has supported the fact that abnormal pressure areas propagate within the rock mass. The listed parameters vary from a seam up to the surface normally both towards the rock mass and towards the mined-out area along with the stope advance. The abovementioned helps define parameters of stratification cavity formation within the roof rocks of an extraction pillar since the cavities may accumulate mine methane. Originality. Dependencies of the changes in rock layer subsidence height have been derived based upon formation dynamics of the mined-out longwall volume. Regularities of changes in volumes of rock formation stratification cavities have been identified depending upon the strength and thickness of the rock layers; closeness to mining area; and stope advance velocity as well as its length. Practical value. Based upon the method by Professor O.V.Savostyanov, an algorithm has been proposed to define possible mine methane accumulations after mining operations within the extraction pillar are completed. Hence, the areas of methane accumulation will be considered in future as extra sources of fuel material. At the same time, it has been proposed to complement operation mode of a mining enterprise with biogas plants if the produced mine mixture is poor. A technological scheme for the combined mine methane-biogas extraction has been provided.