Method for preventing rock burst

Abstract

The present application relates to the technical field of coal mine, specifically relates to a rock burst prevention method, the rock burst prevention method, it includes: the position of drilling hole is the position of the preset distance from the working face stop mining line, and the position of drilling hole is adjacent to the roadway group relative to the stop mining line, according to the length of working face determines the drilling hole quantity and drilling hole azimuth and inclination of stop mining coal pillar area of transport crossheading and air return crossheading, according to the geological conditions of coal seam roof and the azimuth and inclination of drilling hole determine the depth of drilling hole, according to the depth of drilling hole determines the charge quantity in hole and carries out pre-splitting blasting to roof, the present application proposes a rock burst prevention method, which can reduce the risk of rock burst.

Description

Technical Field

[0001] This invention relates to the field of coal mining technology, and specifically to a method for preventing rockbursts. Background Technology

[0002] When a coal mine reaches the final mining area of ​​the working face, the working face is under high stress concentration due to the concentrated arrangement of the mining roadways, connecting roadways, chambers, and preparation roadways. The pressure of the working face's advance support, the tectonic stress, and the concentrated stress of the dense roadway cluster are repeatedly superimposed. When the working face is disturbed again, the dynamic load caused by the roof movement and tectonic activation will cause the roof of the working face and the roof of the roadway group to be under high stress concentration, which can easily induce rockburst and threaten mine safety. Summary of the Invention

[0003] This invention aims to at least partially address one of the technical problems in related technologies. To this end, embodiments of this invention propose a method for preventing rockbursts, which can reduce the risk of rockbursts.

[0004] The rockburst prevention method of this invention includes: determining the location of a borehole, wherein the location of the borehole is a predetermined distance from the stop-mining line of the working face, and the location of the borehole is relative to the adjacent roadway group of the stop-mining line; determining the number of boreholes and the azimuth and dip angle of the boreholes in the stop-mining coal pillar area of ​​the transport roadway and return air roadway according to the length of the working face; determining the depth of the borehole according to the geological conditions of the coal seam roof and the azimuth and dip angle of the borehole; and determining the amount of explosives in the borehole according to the depth of the borehole to perform pre-splitting blasting on the roof.

[0005] The rockburst prevention method of this invention can reduce the risk of rockburst.

[0006] In some embodiments, the number of holes is multiple, and the multiple holes are divided into two groups, with the two groups of holes symmetrically arranged in the coal pillar areas of the transport roadway and the return air roadway.

[0007] In some embodiments, the vertical distance between one end of the plurality of holes away from the transport roadway or the return air roadway and the transport roadway or the return air roadway is the same.

[0008] In some embodiments, the plurality of holes are spaced apart along the length of the working face, and the number of holes located on the top plate of the working face is greater than the number of holes located on the top plate of the coal pillar area.

[0009] In some embodiments, the depth of the hole located on the top plate of the working face gradually increases in the direction away from the coal pillar area, and the depth of the hole located on the top plate of the coal pillar area gradually increases in the direction away from the working face.

[0010] In some embodiments, the inclination angle of the hole located on the top plate of the working face gradually decreases in the direction away from the coal pillar area, and the inclination angle of the hole located on the top plate of the coal pillar area gradually decreases in the direction away from the working face.

[0011] In some embodiments, after explosives are placed in the hole to form a charge section, the hole is sealed to form a sealing section. The length of the sealing section is A, the depth of the borehole is B, and (1 / 3)×B≤A≤(1 / 2)×B.

[0012] In some embodiments, the length of the charge section is C, (1 / 3)×B≤C≤(1 / 2)×B, and A+C=B.

[0013] In some embodiments, the geological conditions of the coal seam roof include roof lithology and roof thickness.

[0014] In some embodiments, the preset distance is 250-300 meters. Attached Figure Description

[0015] Figure 1 This is a schematic flowchart of the rockburst prevention method according to an embodiment of the present invention.

[0016] Figure 2 This is a schematic diagram of the drilling location according to an embodiment of the present invention.

[0017] Figure 3 This is a cross-sectional view of the drilling location according to an embodiment of the present invention.

[0018] Figure label:

[0019] Transport roadway 100, return air roadway 200, transport roadway stop-mining pillar area 300, return air roadway stop-mining pillar area 400, working face stop-mining line 500.

[0020] Lane group 1, First auxiliary transport lane 11, First return air lane 12, Second return air lane 13, Second auxiliary transport lane 14

[0021] Hole 2 (first hole), Hole 3 (second hole), Hole 4 (third hole), Hole 5 (fourth hole), Hole 6 (fifth hole), Hole 7 (sixth hole). Detailed Implementation

[0022] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0023] like Figure 1As shown, the rockburst prevention method of this invention includes: determining the location of a borehole, wherein the location of the borehole is a preset distance 500 from the stop line of the working face, and the location of the borehole is relative to the adjacent roadway group 1 of the stop line; determining the number of boreholes and the azimuth and dip angle of the boreholes in the stop coal pillar areas of the transport roadway 100 and the return air roadway 200 according to the length of the working face; determining the depth of the boreholes according to the geological conditions of the coal seam roof and the azimuth and dip angle of the boreholes; and determining the amount of explosives in the boreholes according to the depth of the boreholes to perform pre-splitting blasting on the roof.

[0024] Specifically, by determining the number of boreholes, borehole azimuth, dip angle, and depth in the 300th and 200th coal pillar areas of the transport roadway and the return air roadway, boreholes are drilled at a predetermined distance of 500 from the working face's stop line. Different amounts of explosives are placed in the boreholes at different locations to pre-splitting the roof. By pre-splitting the roof of the 300th and 400th coal pillar areas of the transport roadway and the return air roadway, the connection between the working face and the roadway group 1 area is severed, stress transmission is blocked, and the roadway group 1 area is placed in a low-stress zone. This reduces the disturbance impact of the working face's mining on the roadway group 1, lowers the risk of rockburst, and allows the working face to be safely mined back to the working face stop line 500.

[0025] It should be noted that roadway group 1 includes, but is not limited to, the first auxiliary haulage roadway 11, the second auxiliary haulage roadway 14, the first return air roadway 12, the second return air roadway 13, the conveyor belt roadway, and the intersection of each roadway. The haulage roadway 100 extends in the front-back direction, and the return air roadway 200 also extends in the front-back direction. Roadway group 1 is located at the front end of the working face stop line 500. The location of the borehole is relative to the setting of roadway group 1 adjacent to the stop line, that is, the location of the borehole is located between the stop line and roadway group 1. This can ensure that the roof blasting cuts off the connection between the working face and roadway group 1, reduce the disturbance of the working face at the end of mining to roadway group 1, and thus reduce the risk of rockburst.

[0026] The length of the working face is the distance between the transport roadway 100 and the return air roadway 200 in the left and right directions. The transport roadway 100 is located at the left end of the working face, and the return air roadway 200 is located at the right end of the working face. The number of boreholes is determined according to the length of the working face to determine the length of the working face that can be covered by borehole blasting, thereby cutting off the connection between the working face and the roadway group 1.

[0027] For example, drilling can begin at a distance of more than 300 meters from the stop line to avoid blasting affecting the mining operation of the working face. Before the mining disturbance of the working face affects roadway group 1, drilling and blasting can be carried out on the roof above the stop coal pillar area to cut off the connection between the working face and roadway group 1, so that roadway group 1 is in a low stress area, weakening the dynamic load formed by roof fracture, raising the threshold for rockburst occurrence, and significantly reducing the risk of rockburst.

[0028] In this embodiment of the invention, the roof of the coal pillar area in the cessation of mining is pre-fractured by drilling at a preset distance of 500 meters from the cessation line of the working face. On the one hand, this reduces the superposition of the pre-support pressure, structural stress and concentrated stress of the dense roadway group 1 of the working face. On the other hand, it weakens the dynamic load formed by the roof fracture, thereby avoiding the superposition of highly concentrated dynamic and static loads and reducing the risk of rockburst.

[0029] In some embodiments, there are multiple holes, which are divided into two groups. The two groups of holes are symmetrically arranged in the coal pillar areas of the transport roadway 100 and the return air roadway 200.

[0030] Specifically, such as Figure 2 and Figure 3 As shown, the multiple holes are divided into two groups. One group is located above the coal pillar area 300 of the transport roadway, and the other group is located above the coal pillar area 400 of the return air roadway. The two groups of holes are symmetrically arranged in the coal pillar areas 300 of the transport roadway and 400 of the return air roadway with the center line of the working face as the symmetrical line. The symmetrical arrangement of the multiple holes ensures that the blasting of the multiple holes can cut off the connection between the working face and the roadway group 1 area and block the stress transmission.

[0031] For example, the number of holes is set to 12, divided into two groups, with 6 holes in each group: Hole 2 (first hole), Hole 3 (second hole), Hole 4 (third hole), Hole 5 (fourth hole), Hole 6 (fifth hole), and Hole 7 (sixth hole). The holes are fan-shaped blasting holes. Holes 2 and 3 are located on the roof of the coal pillar where mining has stopped, while Holes 4, 5, 6, and 7 are located on the roof of the working face. It can be understood that the number of holes can also be set to 16, with 8 holes in each group, three holes on the coal pillar where mining has stopped and five holes on the working face. This embodiment of the invention does not limit the specific number and distribution of the holes, and the actual implementation shall prevail.

[0032] In some embodiments, the vertical distance between the ends of the plurality of holes away from the transport roadway 100 or the return air roadway 200 and the transport roadway 100 or the return air roadway 200 is the same.

[0033] Specifically, such as Figure 2 and Figure 3 As shown, multiple holes extend from the top plate along the interior of the top plate, that is, the holes extend vertically. The actual extension direction of the holes is adjusted according to the azimuth and inclination angle of the holes. The upper ends of the multiple holes are at the same horizontal level. The vertical distance between the upper ends of the multiple holes and the transport roadway 100 or the return air roadway 200 is the same, ensuring that the blasting center of the multiple holes is at the same height, which facilitates cutting off the connection between the working face and the roadway group 1, thereby reducing the risk of rockburst.

[0034] In some embodiments, a plurality of holes are spaced apart along the length of the working face, and the number of holes located on the top plate of the working face is greater than the number of holes located on the top plate of the coal pillar area.

[0035] Specifically, multiple holes are arranged at intervals along the left and right direction, and the number of holes on the working face roof is greater than the number of holes in the coal pillar area. Since working face disturbances can easily cause the working face roof and the roadway group 1 roof to be in a state of high stress concentration, by cutting off the connection between the working face and roadway group 1, roadway group 1 is placed in a low stress area.

[0036] For example, the number of holes in the working face roof is four and the number of holes in the coal pillar area roof is two, or the number of holes in the working face roof is six and the number of holes in the coal pillar area roof is three. By adjusting the number of holes in the working face roof and the number of holes in the coal pillar area roof, the explosive blasting in the holes can sever the connection between the working face and roadway group 1.

[0037] For example, the greater the difference between the dimensions of the working face in the left-right direction and the dimensions of the coal pillar area in the left-right direction, the greater the difference between the number of holes in the top plate of the working face and the number of holes in the top plate of the coal pillar area; conversely, the smaller the difference between the dimensions of the working face in the left-right direction and the dimensions of the coal pillar area in the left-right direction, the smaller the difference between the number of holes in the top plate of the working face and the number of holes in the top plate of the coal pillar area.

[0038] In some embodiments, the depth of the hole located on the top plate of the working face gradually increases in the direction away from the coal pillar area, and the depth of the hole located on the top plate of the coal pillar area gradually increases in the direction away from the working face.

[0039] Specifically, since the drilling site is located in the coal pillar area where mining has stopped, the upper ends of multiple holes are on the same horizontal line, and the upper ends of multiple holes are arranged at intervals in the left and right directions. This results in the depth of holes far from the drilling site being greater than the depth of holes adjacent to the drilling site. That is, the smaller the vertical distance between the upper end of the hole and the drilling site in the left and right directions, the shallower the hole is; the larger the vertical distance between the upper end of the hole and the drilling site in the left and right directions, the deeper the hole is. This ensures that when the explosives in the hole are detonated, the connection between the working face and roadway group 1 can be severed, thereby reducing the risk of rockburst.

[0040] Optionally, since the first hole 2 and the second hole 3 are located on the roof of the coal pillar area, the depth of the first hole 2 is greater than the depth of the second hole 3. The third hole 4, the fourth hole 5, the fifth hole 6 and the sixth hole 7 are located on the roof of the working face, so the depth of the third hole 4 is less than the depth of the fourth hole 5, the depth of the fourth hole 5 is less than the depth of the fifth hole 6, and the depth of the fifth hole 6 is less than the depth of the sixth hole 7.

[0041] Because multiple holes are symmetrically arranged in the transport roadway 100 and the return air roadway 200, that is, the first hole 2 on the transport roadway 100 side and the first hole 2 on the return air roadway 200 side have the same hole depth, the second hole 3 on the transport roadway 100 side and the second hole 3 on the return air roadway 200 side have the same hole depth, the third hole 4 on the transport roadway 100 side and the third hole 4 on the return air roadway 200 side have the same hole depth, the fourth hole 5 on the transport roadway 100 side and the fourth hole 5 on the return air roadway 200 side have the same hole depth, the fifth hole 6 on the transport roadway 100 side and the fifth hole 6 on the return air roadway 200 side have the same hole depth, the sixth hole 7 on the transport roadway 100 side and the sixth hole 7 on the return air roadway 200 side have the same hole depth, and the upper ends of the holes on the transport roadway 100 side and the holes on the return air roadway 200 side are all on the same horizontal line.

[0042] It should be noted that drilling can be carried out through one or more drilling sites. In this embodiment of the invention, two drilling sites are used for drilling. One drilling site is set up in the coal pillar area of ​​the transport roadway 100 to drill two blasting holes on the side of the coal pillar of the transport roadway 100 and four blasting holes on the side of the working face. The other drilling site is set up in the coal pillar area of ​​the return air roadway 200 to drill two blasting holes on the side of the coal pillar of the return air roadway 200 and four blasting holes on the side of the working face.

[0043] In some embodiments, the inclination angle of the holes located on the top plate of the working face gradually decreases in the direction away from the coal pillar area, and the inclination angle of the holes located on the top plate of the coal pillar area gradually decreases in the direction away from the working face.

[0044] Specifically, such as Figure 2 and Figure 3 As shown, the inclination angle of the holes located on the side of the transport roadway 100 and on the top plate of the working face gradually decreases in the direction away from the coal pillar area, that is, it gradually decreases from left to right. The inclination angle of the holes located on the side of the transport roadway 100 and on the top plate of the coal pillar area gradually decreases in the direction away from the working face, that is, it gradually decreases from right to left.

[0045] The inclination angle of the holes located on the 200 side of the return air roadway and on the top plate of the working face gradually decreases in the direction away from the coal pillar area, that is, gradually decreases from right to left.

[0046] In some embodiments, after explosives are placed into the hole to form a charge section, the hole is sealed to form a sealing section. The length of the sealing section is A, the depth of the hole is B, and (1 / 3)×B≤A≤(1 / 2)×B.

[0047] Specifically, after placing explosives into the hole, the hole is sealed to ensure the explosives are positioned at a predetermined location within the hole, thus guaranteeing the explosive's detonation effect. This embodiment of the invention ensures the explosive's detonation effect by limiting the distance between the sealing section and the depth of the borehole.

[0048] When the length of the sealing section is less than 1 / 3 of the borehole depth, blasting is likely to affect the lower end of the roof, thus affecting the mining of the working face. When the length of the sealing section is greater than 1 / 2 of the borehole depth, the amount of explosives in the hole is not enough to ensure the severing of the connection between the working face and roadway group 1, thus increasing the risk of rockburst.

[0049] In some embodiments, the length of the charge section is C, (1 / 3)×B≤C≤(1 / 2)×B, and A+C=B.

[0050] Specifically, by placing explosives in the borehole and adjusting the ratio between the length of the charge section and the depth of the borehole, it is ensured that when the explosives in the charge section blast, the connection between the working face and roadway group 1 can be severed without affecting the mining of the working face, thereby reducing the risk of rockburst.

[0051] The explosive charge is located at the upper end of the hole, and the sealing section is located at the lower end of the hole. By adjusting the ratio between the sealing section and the charge section in different holes, the blasting effect of different holes can be adjusted.

[0052] In some embodiments, the geological conditions of the coal seam roof include roof lithology and roof thickness.

[0053] Specifically, the lithology of the top plate, from bottom to top, consists of coarse-grained sandstone, mudstone, and coarse-grained sandstone. The upper end of the borehole extends into the upper coarse-grained sandstone, and the lower end of the borehole is connected to the lower coarse-grained sandstone as the sealing section. The section between the mudstone and the upper coarse-grained sandstone is the charging section.

[0054] For example, the vertical distance between the lower end of the hole and the lower end of the mudstone is 14 meters, and the vertical distance between the upper end of the hole and the lower end of the mudstone is 16 meters.

[0055] In some embodiments, the preset distance is 250-300 meters.

[0056] Specifically, the preset distance refers to the preset distance of 500 meters from the working face stop line. By setting the preset distance, the location of the borehole can be determined, thereby better severing the connection between the working face and roadway group 1.

[0057] For example, the preset distances can be 250 meters, 260 meters, 275 meters, 280 meters, 290 meters, or 300 meters.

[0058] For example, if the coal seam thickness at the working face is 10 meters and the stop-mining coal pillar is 250 meters, as the working face gradually approaches the dense roadway group 1, the pre-support pressure of the working face, the tectonic stress, and the support pressure of roadway group 1 are superimposed, resulting in a significant increase in the support pressure of this part of the coal body. Under the disturbance of the working face, the roof fractures and faults are activated, forming a certain scale of dynamic load. The superposition of dynamic and static loads can easily induce rockburst. By carrying out deep-hole blasting to fracturize the roof in the stop-mining coal pillar area of ​​the working face in advance, the dynamic and static load levels in the dense roadway group 1 area can be reduced, and the working face transport roadway can be improved. Roof pre-splitting blasting was carried out in the 300-meter coal pillar area and the 400-meter coal pillar area of ​​the return air roadway. Two drilling sites were set up, with six fan-shaped blasting holes in each site to intensively pre-split the thick and hard roof. Specifically, there were two fan-shaped blasting holes on the roof of the coal pillar side and four fan-shaped blasting holes on the roof of the working face. The diameter of the drill holes was 75 mm. The depth of the first hole 2 on the 200-meter side of the return air roadway was 37 meters, the second hole 3 was 31 meters, the third hole 4 was 32 meters, the fourth hole 5 was 43 meters, the fifth hole 6 was 61 meters, and the sixth hole 7 was 89 meters. The dip angle of the first hole 2 on the 200-meter side of the return air roadway was 55 degrees, the second hole 3 was 75 degrees, the third hole 4 was 70 degrees, the fourth hole 5 was 45 degrees, the fifth hole 6 was 30 degrees, and the sixth hole 7 was 20 degrees. The azimuth of the first borehole 2 located on the 200 side of the return air roadway is 90 degrees, the azimuth of the second borehole 3 is 90 degrees, the azimuth of the third borehole 4 is 270 degrees, the azimuth of the fourth borehole 5 is 90 degrees, the azimuth of the fifth borehole 6 is 270 degrees, and the azimuth of the sixth borehole 7 is 270 degrees. The charge weight of the first borehole 2 on the 200 side of the return air roadway is 58 kg, the charge weight of the second borehole 3 is 47 kg, the charge weight of the third borehole 4 is 50 kg, the charge weight of the fourth borehole 5 is 66 kg, the charge weight of the fifth borehole 6 is 94 kg, and the charge weight of the sixth borehole 7 is 135 kg. By performing deep-hole blasting to fracture the roof above the coal pillar that is not being mined, an artificial fracture zone is created, effectively blocking the impact of mining disturbance on the working face, reducing the increase in dynamic and static loads, and thus reducing the risk of rockburst.

[0059] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0060] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0061] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0062] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that they are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0063] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0064] It is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preventing rockburst, characterized in that, include: The location of the borehole is determined, which is a predetermined distance from the stop line of the working face, and the location of the borehole is relative to the adjacent roadway group of the stop line; The number of boreholes, as well as the azimuth and dip angles, are determined based on the length of the working face for the coal pillar areas of the transport roadway and return air roadway. The depth of the borehole is determined based on the geological conditions of the coal seam roof and the azimuth and dip angle of the borehole. The amount of explosives in the hole is determined based on the drilling depth, and the top plate is pre-splitting blasted. The plurality of holes are distributed at intervals along the length of the working face, and the number of holes located on the top plate of the working face is greater than the number of holes located on the top plate of the coal pillar area; The depth of the hole located on the top plate of the working face gradually increases in the direction away from the coal pillar area, and the depth of the hole located on the top plate of the coal pillar area gradually increases in the direction away from the working face. The inclination angle of the hole located on the top plate of the working face gradually decreases in the direction away from the coal pillar area, and the inclination angle of the hole located on the top plate of the coal pillar area gradually decreases in the direction away from the working face. After placing explosives into the hole to form a charging section, the hole is sealed to form a sealing section. The length of the sealing section is A, the depth of the borehole is B, and (1 / 3)×B≤A≤(1 / 2)×B; The length of the charge section is C, (1 / 3)×B≤C≤(1 / 2)×B, and A+C=B.

2. The method for preventing rockbursts according to claim 1, characterized in that, The number of holes is multiple, and the multiple holes are divided into two groups. The two groups of holes are symmetrically arranged in the coal pillar areas of the transport roadway and the return air roadway.

3. The method for preventing rockbursts according to claim 2, characterized in that, The vertical distance between the ends of the plurality of holes away from the transport roadway or the return air roadway and the transport roadway or the return air roadway is the same.

4. The method for preventing rockbursts according to claim 1, characterized in that, The geological conditions of the coal seam roof include roof lithology and roof thickness.

5. The method for preventing rockbursts according to claim 1, characterized in that, The preset distance is 250-300 meters.

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