Assessment of sudden soil faults hazard when developing a coal seam

Abstract

Purpose. Development of a methodology for assessing the occurrence of sudden fractures in the soil on the example of the development of seam d6 of the Karaganda coal basin. Methodology. Theoretical and experimental studies on the gas content of a coal seam, analysis of technologies for its development. Findings. Studies have shown that sudden fractures of the overworked massif with and without a breakthrough of methane are of the same nature. A necessary condition for the formation of sudden fractures of the seam soil (SFSS) in a mine is the presence of a pack of coal or rock with reduced strength and high gas content in the soil; in this case, the breakthrough of methane into the development occurs only if the cracks formed in the soil of the workings reach the sources of gas release gas-bearing layers (interlayers) of coal. Originality. A predictive indicator of the hazard of the occurrence of SFSS in the working face is proposed, a dimensionless criterion which is the product of dimensionless coefficients reflecting the influence of the development depth, gas content of the seam, the width of the bottomhole zone, the thickness of the protective layer, the thickness of the crumpled coal pack of the lower layer, longwall withdrawal from the assembly chamber, the length of the working face. A nomogram is developed for assessing the risk of SFSS in the development of reservoir d6. Practical value. According to the results of the research, it was proposed to predict the SFSS at the design stage, for the early implementation of regional measures for their prevention. To assess the WSP, a nomogram is to be used for the prevention of SFSS, which includes advanced development of protective seams, measures to reduce the ability to delaminate coal in the lower layer, change in technology for coal mining with intensive degassing of the developed seam and use of interval hydraulic fracturing.