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Method for weakening coal-rock mass by hydraulic blasting and fracturing

A hydraulic blasting and hydraulic fracturing technology, which is applied in the direction of mining fluid, earthwork drilling, and discharge machinery, etc., can solve problems such as difficult to control the expansion of cracks in holes, weakening the effect of top coal or roof, and easy to cause danger due to poor control , to achieve wide practicability, convenient construction, and the effect of preventing rock burst

Active Publication Date: 2010-02-10
CHINA UNIV OF MINING & TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] In the process of coal mining, if the top-coal caving mining method is adopted, it will be difficult to release the top-coal when encountering a hard top-coal, and measures must be taken to loosen the overlying coal to allow the top-coal to be released. One of the current treatment methods is Drilling directly, and then blasting with explosives to loosen the top-coal or roof, but this method is less effective for weakening the top-coal or roof, and if the amount of charge is not properly controlled, it will easily cause safety hazards; the second is to simply use hydraulic fracturing This method needs to inject a very large water pressure, it is difficult to control the expansion of cracks in the hole, and the number of large cracks caused by hydraulic fracturing is small, and the operation requirements are relatively high. If the control is not good, it will easily cause danger; In this case, it is necessary to master the direction and length of the crack propagation and its relationship with time in the three stages of initiation, propagation and instability propagation of the circular hole hydraulic fracture.

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  • Method for weakening coal-rock mass by hydraulic blasting and fracturing

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Embodiment 1

[0013] Embodiment one: the average thickness of a certain mine coal seam is 4m, and the hardness of coal seam 2 is f=3, is nearly horizontal coal seam 2, and the overlying strata is hard sandstone 1, and its average thickness 25m, coal seam of coal mining working face under the coal mine In 2, a drilling rig is used to drill a hydraulic fracturing weakening drill hole 3 toward the roof, the depth of the drill hole 3 is 20m, and the hole diameter is 60mm. The spacing of the holes is about 15m, and the water gel explosive 4 is put into the holes, and the charge is 40g. Lead the lead wire 5 to the outside of the borehole, then use the hole sealer 6 or cement mortar to seal the borehole opening, and then inject high-pressure water into the borehole through the high-pressure water injection pipe 7 to ensure that no hydraulic cracks occur. Stop water injection, detonate water glue 4 explosives and carry out hydraulic blasting. Under the action of blasting pressure, the surrounding r...

Embodiment 2

[0014] Embodiment two: the average thickness of a certain coal mine seam is 9m, the hardness of coal seam 2 is f=4, is a nearly horizontal coal seam, and the mining ratio is 1: 2, and in the coal seam 2 of the coal mining face in the coal mine, a drilling rig is used to move toward Drill holes 3 on the roof, the depth of the holes 3 is 50m, the diameter of the holes is 60mm, and the distance between the holes is 15m. Put water gel explosive 4 in the hole, the charge is 60g, lead the lead wire 5 out of the drill hole, then use the hole sealer 6 or cement mortar to seal the drill hole, and then pass the high-pressure water injection pipe 7 to Inject high-pressure water into the borehole, subject to no hydraulic cracks, stop the water injection, detonate the water gel explosive 4 to carry out hydraulic blasting, under the action of the explosion pressure, the surrounding rock of the borehole will be broken, and a large amount of water will be generated around the borehole. Cracks...

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Abstract

The invention discloses a method for weakening coal-rock mass by hydraulic blasting and fracturing. The structure of coal-rock mass can be changed by adopting hydraulic blasting and fracturing. The method comprises the following steps: drilling a hole in a coal layer, and placing water-gel explosive in the hole; and then sealing the hole and injecting water into the hole to a set pressure; stopping water injection based on the standard that no hydraulic fracture is generated; detonating the explosive and carrying out hydraulic blasting to lead the wall rock of the drilling hole to burst; generating a great number of fractures on the periphery of the drilling hole; and then carrying out hydraulic fracturing; expanding along exploding fracture under the action of hydraulic pressure of the fracture, and forming a great number of hydraulic pressure fractures. The method of the invention not only can effectively weaken the strength of the coal-rock mass, can reduce wall rock stress of the weakening area, but also can improve ventilation property of the coal layer; is an effective technical way of improving the top coal caving, preventing impact mine pressure, preventing coal and gas burst, and improving efficiency of gas extraction in coal mine. The method has simple process, convenient construction, reliable safety, easy operation and good control.

Description

technical field [0001] The invention relates to a hydraulic fracturing weakening method, in particular to a hydraulic blasting fracturing weakening method for coal and rock mass. Background technique [0002] In the process of coal mining, if the top-coal caving mining method is adopted, it will be difficult to release the top-coal when encountering a hard top-coal, and measures must be taken to loosen the overlying coal to allow the top-coal to be released. One of the current treatment methods is Drilling directly, and then blasting with explosives to loosen the top-coal or roof, but this method is less effective for weakening the top-coal or roof, and if the amount of charge is not properly controlled, it will easily cause safety hazards; the second is to simply use hydraulic fracturing This method needs to inject a very large water pressure, it is difficult to control the expansion of cracks in the hole, and the number of large cracks caused by hydraulic fracturing is sma...

Claims

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Application Information

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IPC IPC(8): E21C37/12E21B43/263
Inventor 黄炳香刘长友程庆迎
Owner CHINA UNIV OF MINING & TECH
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