{'fraction_non_alphanumeric': 0.02585258525852585, 'fraction_numerical': 0.0, 'mean_word_length': 4.867741935483871, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Integrated technology for multistage drainage of coal seams before high-rate cutting

An increase in the depth of underground coal mining leads to an increase in gas content, to a decrease in gas permeability, and, as a result, to a decrease in the mine drainage efficiency. The article presents the actual data on implementation of the integrated multistage pre-mine drainage technology using surface and underground boreholes in Kirov Mine of SUEK-Kuzbass. The actual estimate of the improved underground hydraulic fracturing efficiency is made by a number of objective factors identified during underground coal production in the hydraulic fracturing zones and in the check zones. These objective factors are the increase in output per face, decrease in methane emission in longwalls and the reduction in downtime of mining equipment by gas criterion. The study results on the effective parameters of the underground fracturing technology are presented, namely, the fluid injection rate, effective (useful) length of fracturing wells and the fluid injection volume. The article gives the actual data on hydraulic impact exerted on a coal seam unloaded from rock pressure using surface boreholes. It is shown that the main impact mode is hydraulic splitting, sometimes with microhydrofractures created at high rates of fluid injection into the coal seam. The prospects of further improvement in hydraulic coal splitting from ground surface are based on implementation of selfsustaining coal destruction and on using the effect of coal swelling in the process zone. The authors appreciate participation of A. V. Malafeev, I. A. Kurmanov, E. A. Kvitko, V. I. Gavrilov, I. A. Komissarov, S. L. Demin, A. B. Letashkov, I. V. Chaldin and other experts from SUEK-Kuzbass in the preparation and implementation of the tests.