Space and time coordination control weakening method for hard coal seam roof

Abstract

The invention discloses a space and time coordination control weakening method for a hard coal seam roof. The space and time coordination control weakening method comprises the steps that firstly, a plurality of advanced weakening fracturing drilling groups are drilled in sequence in the advance direction of the coal seam working face on the roof of a return air roadway, wherein each advanced weakening fracturing drilling group internally comprises a first row of fracturing drill holes, a second row of fracturing drill holes and a third row of fracturing drill holes which are arranged in sequence in the advance direction of the coal seam working face, and all the three rows of fracturing drill holes are inclined at different angles towards the direction of a goaf; and when the coal seam working face advances to the position of the advanced weakening fracturing drilling groups, the three rows of fracturing drill holes are filled with static crushing agent cartridges in sequence to realize gradual fracturing weakening of the roof rock layer. According to the method, the best effect of the cartridges is achieved by using the free surface to create a free face or a weakening layer, ''gradual weakening + overall fracture '' is achieved, and the space and time coordination fracturing of the drill holes with different tilt angles of the roof is realized, so that the roof caving efficiency is enhanced. The space and time coordination control weakening method for the hard coal seam roof is simple in structure, and the fracturing effect is good.

Description

technical field [0001] The invention relates to a spatio-temporal synergetic control weakening method of a hard coal seam roof, which is especially suitable for high-efficiency fracturing operations of hard roof strata without free space, and realizes the purpose of spatio-temporal synergistic control weakening. Background technique [0002] The caving of the hard roof is one of the effective measures to prevent the abnormal accumulation of gas in the upper corner and reduce the sudden concentration of stress in the overlying strata. The integrity and high strength of the hard and compact roof strata are often the rapid collapse zone of the roof during coal seam mining. There are many obstacles. Conventional roof fracturing measures mainly include high-pressure hydraulic fracturing and deep-hole blasting technology, both of which use high-pressure water or emulsion explosives to crack the roof rock formation, but there are still some shortcomings. For example, high-pressure ...

AI Technical Summary

Problems solved by technology

The common method is to alternately charge a large number of vertical boreholes. On the one hand, the amount of drilling construction is large, and the premise cost is high; Pressure relief space, resulting in poor weakening and fracturing effect

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