Krukovska V.V. Numerical analysis of influence of coal seams water saturation after water injection on their outburst hazard

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Parent Category: Geo-Technical Mechanics, 2022

Category: Geo-Technical Mechanics, 2022, Issue 161

Geoteh. meh. 2022, 161, 14-27

https://doi.org/10.15407/geotm2022.161.014

 

NUMERICAL ANALYSIS OF INFLUENCE OF COAL SEAMS WATER SATURATION AFTER WATER INJECTION ON THEIR OUTBURST HAZARD

¹Krukovska V.V.

¹Institute of Geotechnical Mechanics named by N.Poljakov of National Academy of Sciences of Ukraine 

UDC 622.267.53

Language: English

Abstract. The influence of water on the outburst hazard of coal seams by changing the phase permeability and coal properties was investigated. To do this, a numerical model of the gas-dynamic processes in the mine face in the outburst-prone zone near the tectonic fault was developed with taking into account the presence of water in the crack-pore space of coal. Calculations were performed for four cases: without water influence, with the influence of water presence on the change of phase permeability, with its influence on the change of the coefficient of elasticity and Poisson's ratio. Calculation of geomechanical and filtration parameters under conditions of minimum natural moisture saturation s_w = 1% showed that under these boundary and initial conditions there is an outburst of coal and methane in the outburst-hazardous zone. The zone of inelastic deformations rapidly grows from the mine face along the coal seam; pressure gradients near the free surface take very high values; coal and gas outburst takes place and cavity forms. Then geomechanical processes and the process of methane filtration return to the quasi-stationary mode. As a result of calculations with variation of the moisture s_w values in crack-pore space of coal, it was obtained that gas-dynamic processes in the mine face start if s_w < 24%, for the boundary and initial conditions accepted in this work. When this limit is exceeded, geomechanical and filtration processes in the coal seam near the mine face do not start; geomechanical and filtration processes occur in quasi-stationary mode. The effect of moisture on the reduction of phase permeability for methane leads to the neutralization of the outburst-hazardous properties of coal. Additional consideration of the decrease in the coefficient of elasticity and increase in Poisson's ratio due to coal humidification reduces the safe limit of moisture saturation to s_w = 20%. Thus, the regularities of the influence of moisture on the outburst hazard of coal seams were established. The numerical model was developed that allows to identify a safe limit of moisture saturation, at which the nature of geomechanical and filtration processes in the coal seam changes from dynamic to quasi-stationary in specific geological conditions.
Keywords: mining safety, numerical simulation, outburst hazard, permeability to phase, water saturation.

 

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About author:

Krukovska Viktoriia Viktorivna, Doctor of Technical Sciences (D. Sc), Senior Researcher, Senior Researcher in Department of Pressure Dynamics Control in Rocks, 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.

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