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.

1 . A method for over-pit and under-pit cooperative control of roofs of far and near fields of an extra-large stoping space, including a method for controlling a hard roof by means of hydraulic fracturing via an over-pit vertical bore of a far field of an extra-large stoping space, a method for controlling a hard roof by means of hydraulic fracturing via an over-pit L-shaped bore of a far field of an extra-large stoping space, a method for controlling a hard roof via an over-pit strong repeating impact pulse of high energy density of a far field of an extra-large stoping space, a method for controlling a hard roof via down-pit water injection of a near field of an extra-large stoping space, a method for controlling a hard roof via down-pit stratified blasting of a near field of an extra-large stoping space, and a method for controlling a hard roof via weakening by hydraulic fracturing of a near field of an extra-large stoping space; characterized in that the method comprises following steps:
 firstly, the hard roof of the far field is controlled by adopting the method for controlling a hard roof by means of hydraulic fracturing via an over-pit vertical bore of a far field of an extra-large stoping space;   secondly, the hard roof of each target stratum is controlled by adopting the method for controlling a hard roof by means of hydraulic fracturing via an over-pit L-shaped bore of a far field of an extra-large stoping space;   then, the weakened hard roof of each target stratum is further controlled by adopting the method for controlling a hard roof via an over-pit strong repeating impact pulse of high energy density of a far field of an extra-large stoping space;   so far, the over-pit constructive control of the hard roof of the far field of the extra-large stoping space has been completed, simultaneously or successively, the down-pit constructive control of the hard roof of the near field of the extra-large stoping space is conducted, firstly, the near-field hard roof is preliminary controlled by adopting the method for controlling a hard roof via down-pit water injection of a near field of an extra-large stoping space;   then, the near-field hard roof is controlled and weakened in layers by adopting the method for controlling a hard roof via down-pit stratified blasting of a near field of an extra-large stoping space;   finally, the near-field hard roof is controlled by adopting the method for controlling a hard roof via weakening by hydraulic fracturing of a near field of an extra-large stoping space.