Method for calculating explosive amount in coal-pillar-free roof-cutting entry retaining pre-splitting blasting

Abstract

The invention relates to the technical field of coal mining blasting, and in particular relates to a method for calculating explosive quantity in coal-pillar-free roof-cutting entry retaining pre-splitting blasting. The method comprises the steps of 1 obtaining an expression of stress borne by a blast hole wall due to the fact that stress waves are gradually attenuated when being propagated in a rock body, and establishing a seam forming condition taking the tensile strength of the rock as a standard,and obtaining a theoretical expression of the minimum explosive quantity required by seam forming; and 2 considering the stability of the basic roof, establishing a basic roof mechanical model under the dynamic and static coupling effect, analyzing a basic top tensile stress field under the stress wave effect, and constructing a basic roof stability criterion taking the rock tensile strength as a standard to obtain a maximum explosive quantity theoretical expression under the condition ofensuring the stability of the basic roof. The method has the advantages that the maximum explosive load and the minimum explosive load which guarantee the stability of the roof and the joint cutting effect during blasting can be theoretically calculated, a theoretical basis for scientifically selecting the explosive loads and the blast hole spacing is established, and meanwhile, the safety of underground blasting operation is effectively improved.

Description

technical field [0001] The invention relates to the technical field of coal mining blasting, in particular to a method for calculating the amount of explosives in pre-splitting blasting without coal pillars, top cutting and roadway retention. Background technique [0002] The coal pillar-free mining with cut roof and entry retaining cancels the coal pillar retention at the working face, eliminates the artificial filling body constructed by the conventional gob-side entry retaining, greatly simplifies the construction technology, and has important practical significance and broad application prospects. Its core technology is to use pre-splitting blasting to cut off the mechanical connection between the roof of the roadway and the roof of the gob in the advanced working face, so as to achieve the effect of pressure relief. During the pre-splitting blasting, the roadway roof not only bears the static load, but also bears the dynamic load of the blasting, which belongs to the co...

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Problems solved by technology

[0003] The purpose of the present invention is to provide a method for calculating the amount of explosives in the pre-splitting blasting without coal pillars, to solve the problem of coal pillars-free roof cutting and roadway slit effect, charge length, and blast holes proposed in the background technology. The lack of theoretical support for spacing selection

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