Method for intercepting, extracting and releasing pressure gas by blasting anti-reflection directional long drill hole of thick and hard roof rock stratum

Abstract

The invention discloses a method for intercepting, extracting and releasing pressure gas by blasting an anti-reflection directional long drill hole of a thick and hard roof rock stratum. The invention provides a comprehensive treatment method for intercepting, extracting and releasing pressure gas by deep hole presplitting blasting pressure releasing and anti-reflection and directional long drill hole of a working face overlying thick and hard roof rock stratum, the breaking rule of a hard thick-layer roof is analyzed, and a blasting pressure releasing and anti-reflection mechanism is elaborated. Explosive is blasted in a hard rock mass, the blasting stress strength is far higher than the compressive strength of the rock mass, the rock mass around a blasting hole generates a large number of cracks under the action of detonation stress waves, the cracks are completely in a broken state, the integrity of the thick-layer roof is damaged, and vertical gas migration channels of a coal seam and a goaf are increased; and gas flowing into the goaf from an extraction coal seam group is intercepted through the directional long drill hole of the overlying rock stratum of the roof. Meanwhile, the stress around the blasting hole is redistributed, the situation that the fracture distance of the thick and hard roof is too long, and consequently the mine pressure is shown violently is avoided, the additional load of a support is reduced, and the effects of protecting a roadway and improving the drill hole gas extraction rate are achieved.

Description

technical field [0001] The invention relates to the field of gas drainage in coal mines, in particular to a method for gas drainage and pressure relief by blasting thick and hard roof rock layers, increasing penetration, and directional long drilling holes. Background technique [0002] When coal seam groups are mined under thick sandstone, the main factors restricting the safe recovery of the working face are roof control and gas control. With the advancement of the working face, the hard roof forms a large area of ​​overhang after the coal seam is recovered and does not collapse, which increases the stress concentration of the fully mechanized mining hydraulic support and the surrounding rock of the roadway. When a large area of ​​suspended roof falls, it will cause serious damage to the equipment, and it is easy to cause the gas accumulated in the goaf to flow to the coal mining face instantly; The directional gas drainage drilling on the upper hard roof has no cracks in...

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Problems solved by technology

[0004] The purpose of the present invention is to provide a method for blasting thick and hard roof rock formations, increasing penetration, and directional long boreholes to intercept and extract pressure-relieving gas. The stress on the hydraulic support increases, the gas concentration in the upper corner is high, and the safety of the working face is threatened. A deep hole pre-splitting blasting in the thick and hard roof rock layer is proposed to relieve the pressure and protect the roadway. At the same time, the blasting will destroy the thick and hard roof as a whole and increase the gas. The vertical migration channel reduces the additional load of the support and improves the gas drainage rate of the directional long borehole

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