Method for over-pit and under-pit cooperative control of roofs of far and near fields of an extra-large stoping space

Abstract

The invention relates to a control method for a hard roof of a coal mine, specifically to a method for over-pit and under-pit cooperative control of roofs of far and near fields of an extra-large stoping space. The method provided by the invention overcomes the problem of lack of comprehensive and cooperative control methods for hard roofs of far and near fields of an extra-large stoping space in the prior art. According to a technical scheme in the invention, the method comprises an over-pit vertical hole hydraulic fracturing method, an over-pit L-shaped hole hydraulic fracturing method, an over-pit highly-energy-gathered repetition pulse strong shock wave method, an under-pit water injection method, an under-pit layered blasting method and an under-pit hydraulic fracturing method. The method has the advantages that 1) the problem of great mine pressure of the extra-large stoping space is effectively controlled through over-pit and under-pit cooperative control of the hard roofs of far and near fields; 2) advantages of the variety of methods are given to full play and disadvantages of the variety of methods are mutually compensated, so weakening effect on the hard roofs is substantially improved; and 3) all the over-pit and under-pit holes can be used independently or be used in a shared way, so time, manpower, material resources and money used for hole perforation can be greatly reduced.

Description

TECHNICAL FIELD[0001]The present invention relates to a method for controlling a hard roof of a coal mine, and more particularly, to a method for over-pit and under-pit cooperative control of roofs of far and near fields of an extra-large stoping space.BACKGROUND[0002]With the rapid development of coal industry, the intensive and high-efficient production mode has gradually become a normality of coal mining in recent years. En particular, the application of advanced mining techniques, such as large mining height and higher fully-mechanized mining, leads to a substantial increase in the working face length, the oblique length, the coal seam thickness and the height of roof collapse layer, as well as an abnormal collapse fracturing ratio, which consequently renders an extra-large stoping space and extraordinarily unusual intense pressure during production. In this circumstance, the intense stoping pressure has greatly surpassed the pressure caused by hard basic roof. The destabilized ...

AI Technical Summary

Benefits of technology

[0016]A control of the far-field hard roof is realized by successively adopting over-pit vertical bore hydraulic fracturing method, over-pit L-shaped bore hydraulic fracturing method, over-pit strong repeating impact pulse of high energy density method, wherein the proper construction order of the above three methods not only maximizes their individual advantages, but also greatly strengthens their co-actions, which can be embodied as: 1) The vertical bore hydraulic fracturing method is firstly adopted to intensively weaken a part of the far-field hard roof, but it has the defects of limited coverage, usually about several tens of meters in radius, for far-field hard roof of an extra-large stoping space, if vertical bore hydraulic fracturing method is adopted exclusively, multiple vertical bores are needed on the vast mining face, which consumes paramount human resource, material and money; 2) The L-shaped bore hydraulic fracturing method focuses on weakening far-field hard roof of the same target strata, as the L-shaped bore can function within a larger coverage, it effectively makes up the defects of vertical bore hydraulic fracturing method; 3. Strong repeating impact pulse of high energy density hard roof control method is adopted to thoroughly weaken the hard roof of each part and each strata after the preliminary weakening by vertical bore and L-shaped bore hydraulic fracturing.

[0017]Meanwhile, the over-pit control methods can only weaken the far-field hard roof, while the near-field hard roof control must be controlled down-pit by successively adopting down-pit water injection method, down-pit stratified blasting method, and down-pit hydraulic fracturing method. Again, the proper construction order of the above three methods not only maximize their individual advantages, but also greatly strengthen their co-actions, which can be embodied as: 1) Firstly, moisten and weaken the near field hard roof by adopting down-pit water injection method, so as to strengthen the effects of the

Problems solved by technology

En particular, the application of advanced mining techniques, such as large mining height and higher fully-mechanized mining, leads to a substantial increase in the working face length, the oblique length, the coal seam thickness and the height of roof collapse layer, as well as an abnormal collapse fracturing ratio, which consequently renders an extra-large stoping space and extraordinarily unusual intense pressure during production.

The destabilized fracture of high hard ro

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