Hydraulic fracturing pressure relief method for withdrawing channel of underground coal mine coal face

Abstract

The invention relates to the technical field of underground coal mine mining, and discloses a hydraulic fracturing pressure relief method for a withdrawing channel of an underground coal mine coal face. The hydraulic fracturing pressure relief method comprises the following steps of (1) determining structural parameters of a roof rock stratum, and obtaining the influence range and the influence strength of advanced bearing pressure of the coal face; (2) performing primary fracturing when the to-be-fractured rock mass is out of the influence range of the advanced bearing pressure of the coal face so as to form a plurality of hydraulic cracks in the horizontal direction; and (3) performing secondary fracturing when the to-be-fractured rock mass is within the influence range of the advanced bearing pressure of the coal face so as to form a series of hydraulic cracks in the vertical direction, and cutting off the roof rock stratum. According to the hydraulic fracturing pressure relief method for the withdrawing channel of the underground coal mine coal face, a top plate above the withdrawing channel of the underground coal mine coal face can be efficiently and safely crushed, the disturbance of the advanced bearing pressure to surrounding rock of the withdrawing channel is weakened, and normal withdrawing of the coal face during end mining is guaranteed.

Description

technical field [0001] The invention relates to the technical field of underground mining in coal mines, in particular to a hydraulic fracturing pressure relief method for a retraction channel of an underground coal mining face in a coal mine. Background technique [0002] In the final mining stage, the fully mechanized caving coal mining face and the withdrawal channel will be affected by the advanced support pressure, and strong mine pressure will occur, and the roof will collapse and hang in a large area, which will seriously affect the coal mining. The quality of the support during the excavation and withdrawal of the working face and the withdrawal speed of the support after the mining end resulted in serious damage to the support of the coal mining face, and even crushed the conveyor to death, and the coal mining face was forced to stop production. [0003] In the prior art, the drilling and blasting technology is usually used to pre-crack the hard roof in front of the...

AI Technical Summary

Problems solved by technology

[0002] In the final mining stage, the fully mechanized caving coal mining face and the withdrawal channel will be affected by the advanced support pressure, and strong mine pressure will occur, and the roof will collapse and hang in a large area, which will seriously affect the coal mining. The quality of the support during the excavation and withdrawal of the working face and the withdrawal speed of the support after the mining end resulted in serious damage to the support of the coal mining face, and even crushed the conveyor, and the coal mining face was forced to stop production

[0003] In the prior art, the drilling and blasting technology is usually used to pre-crack the hard roof in front of the coal mining face, so as to reduce the stress concentration of the coal and rock mass in front, and reduce the deformation of the roof and surrounding rock of the coal mining face and the withdrawal channel. Patent disclosure The patent No. is CN108661643A, and the patent and patent publication No. CN107060760A is entitled "A method for roof cutting, pressure relief and roadway protection of the retraction channel at the end of mining face" and the title is "A kind of coal mine retraction roadway pre-splitting blasting caving and unloading method". The patent of “Pressure Method” proposes a method of arranging drill holes in rows in the retraction channel, forming penetrating cracks between the drill holes after charge blasting, so as to realize the advanced breaking of the roof. This type of method has the following disadvantages: 1) This type of method Involving detonators, explosives and other pyrotechnics, they need to be specially transported and stored underground, which is not conducive to the economical and efficient production of mines; 2) Blasting in high-gas coal seams has potential safety hazards; Brackets bring impact loads, which is not conducive to roadway maintenance

[0005] The technology close to the present invention is Chinese Patent Publication No. CN107313777A, the patent titled "Mechanized Coal Mining Face Main Retraction Channel Hydraulic Fracturing Pressure Relief Method and Device" proposes a fully mechanized coal mining face main retraction Channel hydraulic fracturing pressure relief method and device, drilling two kinds of boreholes with different parameters obliquely to the roof rock layer in the withdrawal channel, and performing hydraulic fracturing pressure relief treatment at multiple preset positions of the boreholes to form multiple Cutting the cracks, and cutting off the roof strata along the cutting cracks, this method has the following disadvantages: 1) The ground stress state under the site conditions is not considered, although the preset position of the borehole has been cut, the process of hydraulic crack propagation and cracking is oriented, With the expansion of hydraulic cracks, it will be affected by the state of local stress (hydraulic cracks expand along the plane perpendicular to the direction of the minimum stress), and only hydraulic cracks in the same direction can be formed, which can only increase the number of strata layers on the roof, and it is difficult to Cutting off the roof; 2) Arranging two kinds of boreholes at intervals along the axis of the retraction passage, with many boreholes and high labor intensity for workers; 3) Drilling a borehole near the end of the retraction passage in the mining roadway for fracturing coal mining work The top plate at the end of the face shows that the fracturing holes arranged in the withdrawal channel are difficult to fracturing the triangular area at the end, and it is still necessary to arrange drilling holes in the recovery roadway to deal with the roof in the triangular area, which increases the fracturing workload and low production efficiency. A hydraulic fracturing pressure relief method for the withdrawal channel of the underground coal mining face is proposed to solve the above-mentioned problems

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