Frequency reduction and energy reduction method applicable to mining-induced mine tremors in working faces near goaf

Abstract

The present invention relates to the field of rock layer control, and provides a frequency reduction and energy reduction method suitable for mining face induced by mining near goaf. It is mainly aimed at mines with potential danger of mining tremors, and the working face near goaf is depressurized to resolve the potential risks and hazards of mining tremors near goaf. The stability of the main key layer is destroyed by blasting, so that the pressure of the key layer that produces separation is transferred to other areas, thereby alleviating the pressure of the current working face and the adjacent goaf. After the excavation of the drift is completed, the sub-key layer in the position of the pressure zone ahead of the working face to be mined is blasted to relieve the pressure; at the same time, by controlling the amount of explosives and the spacing between blast holes, the integrity of the sub-key layer is maintained, so that the working face to be mined can be mined smoothly and safely. The present invention can effectively resolve the tendency of mining induced by mining near goaf, and provide protection for safe production in coal mines.

Description

Technical Field

[0001] The invention relates to the field of rock layer control, and in particular to a frequency reduction and energy reduction method suitable for mining induced mine tremors in a working face adjacent to a goaf. Background Art

[0002] Mine tremors are common dynamic phenomena in mining activities and are one of the main threats to mine safety. They may induce rock pressure, damage tunnels and equipment, and cause casualties. In order to deal with the potential threat of mine tremors induced by mining at open working faces, the local active emergency relief technologies used mainly include coal seam water injection, large-diameter drilling pressure relief of coal bodies, deep-hole blasting of roof, and hydraulic fracturing of roof. However, for different rock formation conditions, it is necessary to comprehensively consider the drilling location, water injection area, blasting area, hydraulic fracturing area, etc.

[0003] The risk of mining-induced mine tremors in the mining working face mainly comes from the bending deformation of the high-level key layer and the energy accumulation in the advanced pressure zone of the low-level key layer. The patent with publication number CN105626070B provides a deep hole blasting pressure relief method for preventing and controlling rock burst. First, rock burst monitoring is performed in the upper and lower tunnels of the working face of the coal seam with rock burst danger, and the high concentrated stress area is divided to circle the dangerous area; a guide pressure relief tunnel is excavated along the upper tunnel to the center of the dangerous area of ​​rock burst, and blasting pressure relief holes are drilled in the guide pressure relief tunnel along the direction of the roof surrounding rock and the bottom plate surrounding rock. However, this method only relieves pressure on the low-level key layer, which can reduce the rock burst induced by mine tremors underground, but fails to effectively control the induction of mine tremors from the source. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a frequency reduction and energy reduction method suitable for mining-induced mine tremors in working faces adjacent to goafs, which can effectively resolve the tendency of mining-induced mine tremors in working faces adjacent to goafs and provide guarantee for safe production in coal mines.

[0005] The present invention is achieved through the following technical solutions:

[0006] A frequency reduction and energy reduction method for mining induced mine tremors in a working face adjacent to a goaf, comprising the following steps:

[0007] S1, determine the main key layer and the sub-key layer above the adjacent coal seam;

[0008] S2, after the overlying rock strata in the goaf collapse and stabilize, the separation area of ​​the main key layer is explored through drilling;

[0009] S3: Determine the separation zone of the main key layer, and drill multiple blasting holes A from the surface to the boundary position of the separation zone in the main key layer adjacent to the next mining area;

[0010] S4: blasting the blasting hole A so that the cracks formed by the blasting are interconnected;

[0011] S5: Dig a roadway along the goaf on the side of the next mining area close to the goaf, and leave a protective coal pillar;

[0012] S6: In the drift excavated in the next mining area, drill and blast holes B are drilled at regular intervals into the advanced stress bearing zone in the sub-critical layer above the mining area;

[0013] S7: Blasting is performed toward the blasting hole B of the sub-critical layer; the cracks between adjacent blasting holes B are connected, and the length of the cracks in the vertical direction is smaller than the thickness of the sub-critical layer, thereby completing the pressure relief of the mining area.

[0014] Preferably, in S1, the method for determining the main key layer and the sub-key layer above the adjacent coal seam is to drill holes, take cores, determine the thickness of each rock layer and determine the physical properties of each rock layer, and obtain the location and thickness information of the main key layer and the sub-key layer.

[0015] Preferably, in S3, when drilling multiple blasting holes A from the surface to the boundary position of the delamination area in the main key layer adjacent to the next mining area, drilling is performed from the surface in a direction away from the curved sinking area to a direction close to the curved sinking area.

[0016] Furthermore, the bottom positions of the multiple blasting holes A are evenly distributed from top to bottom.

[0017] Preferably, in S4, multiple blasting holes A are filled with explosives and blasted, thereby correspondingly forming multiple blasting hole A fragmentation zones, the cross-sections of the multiple blasting hole A fragmentation zones are all ellipsoidal, and the outer periphery cracks of the multiple blasting hole A fragmentation zones are connected.

[0018] Preferably, in S5, the retained protective coal pillar is reinforced.

[0019] Preferably, in S6, in the drift excavated in the next mining area, blasting holes B are drilled at regular intervals into the advanced stress bearing zone in the subcritical layer above the mining area, wherein the blasting holes B can be drilled in the drift adjacent to the goaf, or in the drift away from the goaf.

[0020] Preferably, explosives are filled in blasting holes B for blasting, correspondingly forming multiple blasting hole B crushing zones, the cross-sections of the blasting hole B crushing zones are all ellipsoidal, and by controlling the amount of explosives and the spacing between the blasting holes, the blasting hole B crushing zones between adjacent blasting holes B are connected in the vertical direction.

[0021] Compared with the prior art, the present invention has the following beneficial technical effects:

[0022] The present invention provides a frequency reduction and energy reduction method for mining induced mine tremors in working faces adjacent to goafs, which is mainly aimed at mines with potential dangers of mine tremors, and decompression is performed on working faces adjacent to goafs to resolve potential risks and hazards of mine tremors in working faces adjacent to goafs. The stability of the main key layer is destroyed by blasting, so that the pressure borne by the key layer that produces separation is transferred to other areas, thereby alleviating the pressure of the current working face and adjacent goafs. After the excavation of the drift is completed, the sub-key layer at the position of the pressure zone ahead of the working face to be mined is blasted to decompress; at the same time, the integrity of the sub-key layer is maintained by controlling the amount of explosives and the spacing between blasting holes, so that the working face to be mined can be mined smoothly and safely.

[0023] Furthermore, an ellipsoidal blasting hole A crushing zone is formed around the blasting hole, which can effectively reduce stress. After the outer cracks are penetrated, the key layer can be cut off, or the cracks in the key layer can be forced to penetrate there, thereby cutting off the transmission path of gravity from the key layer above the goaf to the adjacent mining area.

[0024] Furthermore, when the cracks formed by blasting hole A are interconnected, the key layer above the next mining area forms a cantilever beam, thereby reducing the internal stress at the junction of the coal seam and the goaf, which is conducive to strict control of tunneling, reducing the pressure on the protective coal pillar, and facilitating maintenance. In order to protect the drift 3, the protective coal pillar is reinforced to improve the pressure bearing capacity of the protective coal pillar.

[0025] Furthermore, through blasting, an ellipsoidal blasting hole B crushing zone is formed around the blasting hole, which can effectively resolve the internal stress of the advanced pressure zone and reduce the tendency of rock burst. At the same time, cracks are formed in the blasting hole B crushing zone, and the cracks between adjacent blasting holes B are connected, so that the stress peak of the advanced stress concentration zone formed above the coal seam in the goaf is reduced, and the impact tendency is reduced. The cracks do not penetrate the sub-critical layer, maintaining the integrity of the sub-critical layer. When the working face of the mining area advances forward, it is conducive to the periodic breaking of the sub-critical layer and reduces the pressure on the hydraulic support of the working face. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a lateral schematic diagram of a working face near a goaf in the present invention;

[0027] Figure 2 It is a top view of the sub-critical layer in the present invention.

[0028] In the figure: 10-ground surface; 11-main key layer; 12-sub-key layer; 2-coal seam; 3-slope; 4-protective coal pillar; 5-goaf; 61-blasting hole A; 62-blasting hole A crushing area; 71-blasting hole B; 72-blasting hole B crushing area; 8-working face. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0030] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0031] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0032] See also Figure 1 In one embodiment of the present invention, a frequency reduction and energy reduction method suitable for mining-induced mine tremors in working faces adjacent to goafs is provided, which can effectively resolve the tendency of mining-induced mine tremors in working faces adjacent to goafs and provide protection for safe production in coal mines.

[0033] Specifically, the frequency reduction and energy reduction method applicable to mining induced mine tremors in a working face near a goaf includes the following steps:

[0034] S1, determine the main key layer 11 and the sub-key layer 12 above the adjacent coal seam 2;

[0035] Specifically, the method for determining the main key layer 11 and the sub-key layer 12 above the adjacent coal seam 2 is to drill holes, take core samples, determine the thickness of each rock layer, and determine the physical properties of each rock layer through experiments to obtain the location and thickness information of the main key layer 11 and the sub-key layer 12.

[0036] S2, after the overlying rock formation of the goaf 5 collapses and stabilizes, the separation area of ​​the main key layer 11 is explored by drilling;

[0037] That is, after a mining area is mined, a goaf area 5 is formed. Figure 1As shown, the sub-key layer 12 forms a cantilever beam, and the main key layer 11 bends downward. Generally, due to the large thickness of the main key layer 11, the downward bending degree is smaller than the disturbance of the lower rock layer, and a separation layer will be formed between the main key layer 11 and the rock layer below it. After the separation layer is formed, the weight of the main key layer 11 and the overlying rock layer in the area above the goaf 5 is transferred to the vicinity of the two ends of the separation layer area, and then transmitted downward, causing the rock layer below to have an impact hazard.

[0038] S3: Determine the separation zone of the main key layer 11, and drill a plurality of blasting holes A61 from the ground surface 10 to the boundary position of the separation zone in the main key layer 11 adjacent to the next mining area;

[0039] Specifically, when drilling multiple blasting holes A61 from the surface 10 to the boundary position of the delamination area in the main key layer 11 adjacent to the next mining area, drilling is performed from the surface 10 in a direction away from the curved sinking area to a direction close to the curved sinking area.

[0040] Among them, the bottom positions of the multiple blasting holes A61 are evenly distributed from top to bottom.

[0041] S4: blasting the blasting hole A61 so that the cracks formed by the blasting are interconnected;

[0042] Specifically, multiple blasting holes A61 are filled with explosives for blasting, thereby correspondingly forming multiple blasting hole A fragmentation zones, the cross-sections of the multiple blasting hole A fragmentation zones are all ellipsoidal, and the outer peripheries of the multiple blasting hole A fragmentation zones are connected.

[0043] Among them, after blasting, an ellipsoidal blasting hole A crushing zone 62 is formed around the blasting hole, which can effectively reduce stress. After the outer cracks are penetrated, the key layer can be cut off, or the cracks in the key layer can be forced to penetrate there, thereby cutting off the transmission path of gravity from the key layer above the goaf 5 to the adjacent mining area.

[0044] S5: A roadway is excavated along the side of the next mining area near the goaf 5, and a protective coal pillar is set up; when the cracks formed by the blasting of blast hole A are interconnected, a cantilever beam is formed in the key layer above the next mining area, thereby reducing the internal stress at the junction of the coal seam and the goaf, which is conducive to strict control of roadway excavation, reducing the pressure on the protective coal pillar, and facilitating maintenance. In order to protect the drift 3, the protective coal pillar is reinforced to improve its pressure bearing capacity.

[0045] S6: In the drift 3 excavated in the next mining area, drill and blast holes B71 are drilled at regular intervals into the advanced stress bearing area in the sub-critical layer 12 above the mining area;

[0046] Specifically, in the drift 3 excavated in the next mining area, blasting holes B71 are drilled at regular intervals into the advanced stress bearing zone in the subcritical layer 12 above the mining area, wherein the blasting holes B71 can be drilled in the drift 3 adjacent to the goaf 5, or in the drift 3 on the side away from the goaf 5.

[0047] S7: Blasting is performed toward the blasting hole B71 of the sub-critical layer 12; the cracks between adjacent blasting holes B are connected, and the length of the cracks in the vertical direction is smaller than the thickness of the sub-critical layer 12, thereby completing the pressure relief of the mining area.

[0048] Specifically, explosives are filled in the blasting hole B71 for blasting, and a plurality of blasting hole B fragmentation zones 72 are correspondingly formed. The cross-sections of the blasting hole B fragmentation zones 72 are all ellipsoidal. By controlling the amount of explosives and the spacing between the blasting holes, the blasting hole B fragmentation zones 72 between adjacent blasting holes B71 are connected in the vertical direction.

[0049] By blasting, an ellipsoidal blasting hole B crushing zone 72 is formed around the blasting hole, which can effectively resolve the internal stress of the advanced pressure zone and reduce the tendency of rock burst. At the same time, cracks are formed in the blasting hole B crushing zone 72, and the cracks between adjacent blasting holes B71 are connected, so that the stress peak of the advanced stress concentration zone formed above the coal seam in the goaf is reduced and the impact tendency is reduced. The cracks do not penetrate the sub-critical layer 12, maintaining the integrity of the sub-critical layer 12. When the working face 8 of the mining area advances forward, it is conducive to the periodic breaking of the sub-critical layer 12 and reducing the pressure on the hydraulic support of the working face 8.

[0050] In summary, the present invention is mainly aimed at mines with potential tendency of mine earthquakes, and relieves pressure on the working face adjacent to the goaf 5 to resolve the potential risks and hazards of mine earthquakes in the working face 8 adjacent to the goaf 5. The stability of the main key layer 11 is destroyed by blasting, so that the pressure borne by the key layer that produces separation is transferred to other areas, thereby alleviating the pressure of the current working face and the adjacent goaf 5 area. After the excavation of the longitudinal chute 3 is completed in the working face to be mined, the sub-key layer 12 in the advanced pressure zone above the working face to be mined is blasted to relieve pressure; at the same time, by controlling the amount of explosives and the spacing between blasting holes, the integrity of the sub-key layer 12 is maintained, so that the working face 8 to be mined can be mined smoothly and safely.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for reducing frequency and energy for mining induced earthquakes in working faces near goafs, characterized in that: The steps include: S1, determine the main key layer (11) and the sub-key layer (12) above the adjacent coal seam (2); S2, after the overlying rock strata of the goaf (5) have collapsed and stabilized, the separation area of ​​the main key layer (11) is explored by drilling; S3: determining the separation zone of the main key layer (11), and drilling a plurality of blasting holes A (61) from the ground surface (10) to the boundary position of the separation zone in the main key layer (11) adjacent to the next mining area; When drilling a plurality of blasting holes A (61) from the surface (10) to the boundary position of the separation zone in the main key layer (11) adjacent to the next mining area, the drilling is performed from the surface (10) in a direction away from the curved subsidence zone to a direction close to the curved subsidence zone; The bottom positions of the plurality of blasting holes A (61) are evenly distributed from top to bottom; S4: blasting the blasting hole A (61) so that the cracks formed by the blasting are interconnected; S5: digging a roadway along the goaf on the side of the next mining area close to the goaf (5), and leaving a protective coal pillar; S6: In the drift (3) excavated in the next mining area, blasting holes B (71) are drilled at regular intervals into the advanced stress-bearing zone in the sub-critical layer (12) above the mining area; S7: Blasting is performed toward the blasting hole B (71) of the sub-critical layer (12); the cracks between adjacent blasting holes B are connected, and the length of the cracks in the vertical direction is smaller than the thickness of the sub-critical layer (12), thereby completing the pressure relief of the mining area.

2. The method for reducing frequency and energy of mining induced earthquakes in working faces near goafs according to claim 1 is characterized in that: In S1, the method for determining the main key layer (11) and the sub-key layer (12) above the adjacent coal seam (2) is to obtain the location and thickness information of the main key layer (11) and the sub-key layer (12) by drilling and taking cores to determine the thickness of each rock layer and the physical properties of each rock layer.

3. The frequency reduction and energy reduction method for mining induced mine tremors in a working face near a goaf according to claim 1, characterized in that: In S4, multiple blasting holes A (61) are filled with explosives and blasted, thereby correspondingly forming multiple blasting hole A fragmentation zones (62). The cross-sections of the multiple blasting hole A fragmentation zones are all ellipsoidal, and the outer peripheries of the multiple blasting hole A fragmentation zones are connected.

4. The method for reducing frequency and energy of mining induced earthquakes in working faces near goafs according to claim 1 is characterized in that: In S5, the remaining protective coal pillar (4) is reinforced.

5. The method for reducing frequency and energy of mining induced earthquakes in working faces near goafs according to claim 1, characterized in that: In S6, in the drift (3) excavated in the next mining area, blasting holes B (71) are drilled at regular intervals into the advanced stress-bearing zone in the sub-critical layer (12) above the mining area, wherein the blasting holes B (71) can be drilled in the drift (3) adjacent to the goaf (5), or in the drift (3) on the side away from the goaf (5).

6. The method for reducing frequency and energy of mining induced earthquakes in a working face near a goaf according to claim 1, characterized in that: Explosives are filled in the blasting holes B (71) for blasting, and a plurality of blasting hole B crushing areas (72) are correspondingly formed. The cross-sections of the blasting hole B crushing areas (72) are all ellipsoidal. By controlling the amount of explosives and the spacing between the blasting holes, the blasting hole B crushing areas (72) between adjacent blasting holes B (71) are connected and vertically connected.

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