A method of using high-pressure water jets to induce the overall destruction of overlying residual coal pillars

Abstract

The invention discloses a method for using high-pressure water jets to induce the overall destruction of the overlying residual coal pillars. It firstly determines the width of the elastic core area of ​​the residual coal pillars, thereby determining the damage range of the high-pressure water jets; Divide the area of ​​the elastic core area of ​​the residual coal pillar destroyed by different methods, and after determining the basic parameters of the high-pressure water jet to destroy the residual coal pillar, drill the high-pressure water jet damage area, and then use the ultra-high pressure hydraulic slotting device to weaken the high-pressure water jet, Make the high-pressure water jet damage core area become a plastic zone, and then let the remaining non-water jet damage elastic core area be destroyed by itself under the action of mine pressure; repeat step 4, and finally all the remaining coal pillars along the length are destroyed. The method of the invention can save time and labor and destroy the residual coal pillar in the overlying goaf. There is no limit to the damage form of the left coal pillar itself, and the scope of application is wider.

Description

technical field [0001] The invention relates to the technical field of residual coal pillar destruction in a goaf above a mine stope, in particular to a method for inducing overall destruction of an overlying residual coal pillar by using a high-pressure water jet. Background technique [0002] In the mining process of the upper coal seam of the close-distance coal seam group, in order to prevent air leakage at the working face, water accumulation in the goaf and ensure the stability of the roadway, a 20m-40m wide protective coal pillar will be left between the working faces. , most of the protective coal pillars remain in the goaf due to the influence of mining conditions, and such coal pillars are called residual coal pillars. When the lower coal seam is mined, affected by the stress transfer of the residual coal pillar in the overlying goaf, the mine pressure in the area of ​​the working face below the residual coal pillar is severe, and the safety valve of the support is...

AI Technical Summary

Problems solved by technology

[0004] Chinese Patent Publication No. CN110359909 A discloses a method for softening leftover coal pillars in hard coal seams. The method combines shallow hole pre-splitting blasting technology with hydraulic slotting technology to soften the leftover coal pillars. However, the method involves gunpowder, For inflammable and explosive items such as detonators, explosives storage rooms need to be left underground, and professional management must be arranged at the same time, which poses safety hazards and is not conducive to mine safety, efficiency, and economical production.

The defects of this technology are firstly to drill cores from the upper coal pillars, process the cores into specimens with the same height-to-diameter ratio as the remaining coal pillars, and conduct uniaxial compression tests to confirm whether the failure mode conforms to shear failure. Form, if yes, proceed to the next step (see S1 step), which shows that the technology disclosed by him is only suitable for coal pillars damaged by shearing, and is not suitable for coal pillars damaged by tension, resulting in great limitations in use; the second is Since the position of the weakened coal pillar is selected at the center of the coal pillar, the weakened drill hole here divides the remaining coal pillar into two small coal pillars, and the two small coal pillars serve as support points to bear the pressure of the overlying strata together. When the pillar is narrow, the two small coal pillars divided cannot withstand the pressure of the overlying rock, and the remaining coal pillar is destroyed. However, when the remaining coal pillar is wide, the two small coal pillars divided can withstand the pressure of the overlying rock. pressure, the legacy coal pillars cannot be damaged under the mine pressure, thus determining the most suitable for narrow legacy coal pillars, as it is listed in the specific implementation of the height a and width b coal pillars of 3m and 5m respectively, if used in wide If the remaining coal pillars are left behind, there is a possibility that the remaining coal pillars cannot be destroyed as a whole

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