Kurnosov S.A., Zerkal V.V. Laws of gas draining in the massif disturbed by mining operations
- Details
- Parent Category: Geo-Technical Mechanics, 2019
- Category: Geo-Technical Mechanics, 2019, № 148
Geoteh. meh. 2019, 148, 88-95
https://doi.org/10.1051/e3sconf/201910900047
Laws of gas draining in the massif disturbed by mining operations
1Kurnosov S.A.,2Zerkal V.V.
1Institute of Geotechnical Mechanics named by N. Poljakov of National Academy of Sciences of Ukraine, 2Private Joint Stock Company «DTEK Pavlohradvuhillia»
UDC 622.831.325.3
Language: English
Abstract. A method for calculating gas permeability of the rock massif depending on its stress-strain state is presented. By using methods of the mine experimental studies, influence of mining operations in the adjacent longwalls on intensity of gas release from the previously worked-out long- pillar was determined, as well as impact of the massif stress-strain state on efficiency of the drainage boreholes. Formulas were obtained for calculating coefficients of the impact of zones with static and dynamic abutment pressure on intensity of gas draining in the previously worked- out long-pillar.
The laws, according to which stress-strain state of the rock massif is changed in the process of mining operations, were studied by the mine experimental methods. Experimental studies were conducted in the Zasyadko Mine. Rock cracking was determined by method of electrometry at different distances from the mine roadway. Stress-strain state of the massif was studied by method of local hydraulic fracturing and by method of boreholes. Data on the methane-air mixture and methane flow rates were provided by the mine ventilation service.
Studies have identified laws of gas draining in the massif disturbed by mining operations:
– Conjugate zone between the previously worked-out and working long-pillars is a concentrator of static abutment pressure. Therefore, in the previously worked-out long-pillar and with increased distance to its conjugate zone with the working long-pillar, methane flow rate increases by logarithmic dependence.
– In the massif of previously worked-out long-pillar, processes of fracture formation are intensified under the influence of mining operations in the adjacent longwall. Rock breaking is observed above the conjugate zone between the long-pillars. Front abutment pressure forces the gas to drain from the underworked (overworked) rocks and working long-pillar into the previously worked-out long-pillar. With decreased distance to the conjugate zone between the long-pillars, rate of methane flow into the gas-drainage boreholes increases by more than 10 times according to the logarithmic law.
– Equations are obtained for determining coefficient of influence of static and dynamic abutment pressure zones on intensity of gas drainage. This coefficient characterizes rock massif permeability in the previously worked-out long-pillar and takes into account volume of drainage rocks and influx of methane under the influence of mining operations in the adjacent longwall.
Keywords: stress-strain state of the rock massif, gas permeability of the rock massif, long- pillar method for mining coal seams.
References
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About the authors
Kurnosov Serhii Anatoliiovych,doctor of Technical Sciences (Ph.D.), Senior Researcher, Senior Researcher in Department of Mineral Mining at Great Depths, Institute of Geotechnical Mechanics named by N. Poljakov of National Academy of Sciences of Ukraine(IGTM, NAS of Ukraine), Dnipro, Ukraine, This email address is being protected from spambots. You need JavaScript enabled to view it. .
Zerkal Volodymyr Viktorovych, Engineer, Deputy Chief Engineer for the production of the department "Pershotravenske" PrJSC "DTEK Pavlohradvuhillia", Pavlohrad, Ukraine.