Control of the mud pulse method the loosening of coal layers by amplitude-frequency recommendation of acoustic signal by the APSS-1 system

The article presents the research results of parameters of the mud pulse method the loosening of outburst-hazardous coal seams in the faces of development workings system APSS-1. The results of the monitoring and evaluation of the effectiveness of pulse loosening a coal seam in static and pulsed mode of injection fluid, the main provisions of the developed techniques and additions to methods of acoustic control with a view to their use in hydroimpulsive impact. It is established that application of pulsed injection of fluid leads to a decrease in the active phase of the process pulse loosening a coal seam, to increase its efficiency and increase the speed of the output

Evaluation of the cavitation generator efficiency in the hydro impulsive loosening of a coal-bed

The paper presents the results of mining and experimental work, bench tests and theoretical studies of the energy characteristics of the stationary and pulsating fluid flow, which allow to estimate the efficiency of the cavitation generator in the hydro impulsive loosening of an outburst-prone coal-bed. The active stage of the hydro impulsive loosening and the effective range of the amplitude-frequency (AF) spectrum of the generator operation acoustic signal have been established by the AF spectrum of the sound accompaniment of the hydro impulse impact and the backup pressure of the liquid in the well. By calculation for this range the energy characteristics of the static and dynamic components of the pulsating fluid flow were determined. This made it possible to determine that the efficiency of the cavitation generator, all other conditions of the coal-bed hydro loosening being equal, is 4.8–1.2 times higher than the efficiency of the static impact

Specifics of hydro-loosening of coal seams with account of rocks displacement parameters

The analysis of efficiency decline of methods for hydraulic influence on outburst-prone coal seams in the conditions of large depths is represented. The models are considered for parameters calculation of high-pressure liquid injection, based on the hypotheses of the stress-strain state formation of the coal seam; the patterns of rock pressure manifestation as well as calculation discrepancy between the liquid injection pressure and the terms of large depths, are established. It is shown that in the parameters calculation of the high-pressure liquid injection, it is necessary to take the height of the column of rocks which lost their integrity and form the stratification zone in the underworked massif instead of depth Н of the seam mining. It has been established that the efficiency of hydro-loosening depends not only on the injection pressure, but also on the location of borehole filtration part relative to the maximum of abutment zone

Conceptual tendencies to analyze

The paper considers conceptual tendencies concerning the analysis of coal-gas system state within rock mass in front of a mine working stope in the context of hydroimpulsive effect on an outburst-prone coal seam. It has been shown that mining intensification is impossible without the improved efficiency of means indented to avoid gasdynamic phenomena taking into consideration the effect of technogenic factors on operation schedules. It has been determined that since grades of outburst-prone coal are of globular structure, its breakage may involve changes in molecular weight of coal substance and generation of methane and water molecules. In the context of a shear model of undermined rock mass, method of graphical analysis has been applied to determine areas of changes in border angles of demonstration of the initial and maximum deformation under the effect of rock bearing pressure. The determined dependences are described rather reliably by means of similar logarithmic curves which characterizes identity of their nature. Changes in filtration coal characteristics in the context of shear deformations have been considered. It has been proved experimentally that if injection pressure varies, periodically discontinuous fluid flow has initial, stable, and decaying stages being implemented in the forms of cavitation phenomena and high-frequency hydroimpulsive vibration. Sequence of methods to study parameters of hydroimpulsive action, evaluation of its efficiency, and control over a change in coal-gas system state of outburst-prone coal seams have been considered

The results of monitoring of hydroimpulsive disintegration of outburst-prone coal seams using ZUA-98 system

The paper represents the results of monitoring and evaluation of the efficiency of hydroimpulsive disintegration of outburst-prone coal seams in the stopes of development mine workings using a system of sound detecting facilities. Methods of acoustic emission control have been considered as well as the monitoring tasks to evaluate rock mass conditions before the procedure and after it inclusive of the results of sound accompaniment of hydraulic disintegration of the coal seam. It has been determined that the higher concentration of stresses within the rock mass is, the more efficient action of high frequency self-oscillations of cavitation transmitter is on both the fissuring and changes in gas-dynamic state of the coal seam. It has been recommended to apply a mode of impulsive fluid pumping under the conditions where coal seam is in the stress-strain state