A method of cutting corner failure of remaining coal pillars

Abstract

The invention belongs to the field of coal mining, and discloses a corner cutting destroying method of remaining coal pillars. The corner cutting destroying method comprises the following steps: S1, the reserving shape and size of the remaining coal pillars, the vertical distance between bottom plates of the remaining coal pillars and top plates of lower coal seams, and the distance between the centroid of the remaining coal pillars and the centroid of mining roadways of the lower coal seams are additionally explored and measured; S2, positions of cutting bottom corner drill holes and cuttingtop corner drill holes are determined, and the angle and length of the cutting bottom corner drill holes and the cutting top corner drill holes are calculated; and S3, according to calculating results, in the mining roadways of the lower coal seams, the cutting bottom corner drill holes and the cutting top corner drill holes are drilled, and after the drill holes reach the remaining coal pillars,shape cutting is conducted on the outer sides of the remaining coal pillars in the drilling direction till the remaining coal pillars are destroyed under the mine pressure effect. The corner cutting destroying method is high in safety, good in effect and capable of being widely applied to the field of coal mining.

Description

technical field [0001] The invention belongs to the field of coal mining, and in particular relates to a corner-cutting damage method for leftover coal pillars, in particular to carry out corner-cutting treatment on the upper leftover coal pillars, and transform the coal pillar crushing damage form into a shearing damage form, so as to realize the The method of destruction under pressure. Background technique [0002] Due to the limitation of mining level, equipment conditions and geological factors, a large number of coal pillars of various types are left in the process of coal seam mining to support the roof, protect the upper coal seam roadway, and ensure safe production. These coal pillars will remain permanently underground and cannot be extracted, resulting in a large waste of resources. More importantly, the existence of coal pillars will lead to stress concentration, resulting in abnormal mining pressure in the lower coal seam, prone to accidents such as collapse, r...

AI Technical Summary

Problems solved by technology

[0004] (1) High cost

The existing method does not make full use of the force of the top and bottom plates on the coal pillar, and only increases the amount of explosives, fracturing fluid, and low-temperature liquid nitrogen to achieve the overall crushing of the coal pillar, resulting in an excessive amount of materials required for coal pillar destruction and increased costs.

[0005] (2) High technical difficulty

The existing technical method is to destroy the integrity of the coal pillar through pressure, and the compressive strength of the coal pillar is much greater than the shear strength, so a large external force is required to destroy the coal pillar, which increases the technical difficulty

[0006] (3) Low safety and poor effect

The prior art does not take the above factors into consideration, resulting in gas explosion in gobs that are prone to blasting, and there are great safety hazards; while in the process of hydraulic fracturing, fracturing fluid easily flows into gobs through coal pillar fissures, and the damage effect is very poor.

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