Method for preventing and controlling rock burst of working face in coal seam roof roadway through distributed kerf fracturing

Abstract

The invention relates to the technical field of coal mines, in particular to a method for preventing and controlling working face rock burst through distributed kerf fracturing in a coal seam roof roadway, and the method comprises the steps that a target layer is determined according to the characteristics of an overlying rock layer on a working face, the working face is formed between the first mining roadway and the second mining roadway; digging a pressure relief roadway in the target layer, wherein the pressure relief roadway extends in the tunneling direction of the working face and is located between the first mining roadway and the second mining roadway; drilling is conducted in the pressure relief roadway to form pressure relief holes, and the pressure relief holes extend in the inclination direction of the working face and penetrate through a target layer above the mining roadway; and hydraulic fracturing is carried out in the pressure relief holes so as to cover the preset ranges of the two sides of at least one mining roadway in the inclination direction of the mining roadway, the pressure relief effect can be improved, and the stability of the roadway can be improved by means of the method for preventing and treating the rock burst of the working face through distributed kerf fracturing in the coal seam roof roadway.

Description

Technical Field

[0001] The invention relates to the technical field of coal mines, and in particular to a method for preventing and controlling rock bursts on a working surface by distributed cutting and fracturing in a coal seam roof tunnel. Background Art

[0002] The basic stress of the coal seam with rock burst is at a relatively high level. During the mining of the working face, the breaking of the thick and hard roof in the overlying rock strata of the coal seam will produce a large dynamic load disturbance. When the disturbance exceeds the bearing limit of the coal rock, it will induce the impact initiation, which will then cause the rock burst to appear, seriously affecting the mining safety.

[0003] In the related art, the roof is often depressurized in the mining tunnel, but the depressurization is discontinuous and the mining tunnel is still prone to deformation after depressurization. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, the embodiment of the present invention proposes a method for preventing and controlling rock burst in the working face by distributed cutting and fracturing in the coal seam roof roadway, which can improve the pressure relief effect and improve the stability of the roadway.

[0005] The method for preventing and controlling rock burst in a working face by distributed cutting and fracturing in a coal seam roof tunnel according to an embodiment of the present invention comprises: determining a target layer according to the characteristics of the overlying stratum on the working face, the working face being formed between a first mining tunnel and a second mining tunnel; excavating a pressure relief tunnel in the target layer, the pressure relief tunnel extending along the excavation direction of the working face and being located between the first mining tunnel and the second mining tunnel; drilling in the pressure relief tunnel to form a pressure relief hole, the pressure relief hole extending along the inclination direction of the working face and passing through the target layer above the mining tunnel; and performing hydraulic fracturing in the pressure relief hole to cover a preset range on both sides of at least one mining tunnel in its inclination direction.

[0006] The distributed cutting and fracturing method for preventing and controlling rock burst on the working face in the coal seam roof tunnel of the embodiment of the present invention can improve the pressure relief effect and enhance the stability of the tunnel.

[0007] In some embodiments, drilling is performed in the pressure relief tunnel to form pressure relief holes, including: determining the number of pressure relief holes in each row according to the thickness of the target layer, each row of pressure relief holes including at least one first pressure relief hole and at least one second pressure relief hole, the first pressure relief holes and the second pressure relief holes being arranged relatively in the inclination direction of the working face; determining the spacing distance between two adjacent rows of pressure relief holes in the excavation direction of the working face according to the scope of the hydraulic fracturing; drilling multiple pressure relief holes in each row of pressure relief holes using a drilling site, and drilling multiple rows of pressure relief holes according to the spacing distance between two adjacent rows of pressure relief holes.

[0008] In some embodiments, a drilling site is used to drill multiple pressure relief holes in each row of pressure relief holes, including: drilling at one end of the pressure relief tunnel to form at least one first pressure relief hole, the first pressure relief hole extending along the inclination direction of the working face and arranged upwardly inclined, and the terminal hole position of the first pressure relief hole is located on the side of the first mining tunnel away from the second mining tunnel; drilling at the other end of the pressure relief tunnel to form at least one second pressure relief hole, the second pressure relief hole extending along the inclination direction of the working face and arranged upwardly inclined, and the terminal hole position of the second pressure relief hole is located on the side of the second mining tunnel away from the first mining tunnel.

[0009] In some embodiments, the horizontal distance A between the end hole position of the first pressure relief hole and the end of the first mining tunnel away from the second mining tunnel is 15-20m; and / or, the horizontal distance A between the end hole position of the second pressure relief hole and the end of the second mining tunnel away from the first mining tunnel is 15-20m.

[0010] In some embodiments, when there is only one first pressure relief hole in each row of pressure relief holes, the final hole position of the first pressure relief hole is located in the middle position of the target layer in the up and down direction, the angle between the extension direction of the first pressure relief hole and the horizontal plane is B, and 5°≤B≤10°; and / or, when there is only one second pressure relief hole in each row of pressure relief holes, the final hole position of the second pressure relief hole is located in the middle position of the target layer in the up and down direction, the angle between the extension direction of the second pressure relief hole and the horizontal plane is B, and 5°≤B≤10°.

[0011] In some embodiments, when there are multiple first pressure relief holes in each row of pressure relief holes, the multiple first pressure relief holes are arranged at intervals in the up and down directions, and / or, when there are multiple second pressure relief holes in each row of pressure relief holes, the multiple second pressure relief holes are arranged at intervals in the up and down directions.

[0012] In some embodiments, before performing hydraulic fracturing in the pressure relief hole to cover a preset range on both sides of at least one of the recovery tunnels in its inclination direction, the method further includes: cutting the pressure relief hole, the cutting direction extending along the excavation direction of the working face, and / or the cutting direction extending in the up and down direction.

[0013] In some embodiments, slitting the pressure relief hole comprises: using a slitting device to slit a position that is a first preset distance away from the terminal hole position of the pressure relief hole; moving the slitting device back a second preset distance and continuing to slit until the slitting position is between the first mining tunnel and the second mining tunnel, and the horizontal distance between the slitting position and the first mining tunnel and / or the second mining tunnel is greater than a third preset distance.

[0014] In some embodiments, the slit length is 0.5-1 m.

[0015] In some embodiments, after hydraulic fracturing is performed in the pressure relief hole, the method further includes: recovering the working face. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a flow chart of a method for preventing and controlling rock burst on a working face by distributed cutting and fracturing in a coal seam roof tunnel according to an embodiment of the present invention.

[0017] Figure 2 1 is a top view of a pressure relief tunnel according to an embodiment of the present invention.

[0018] Figure 3 yes Figure 2 Sectional view of II.

[0019] Reference numerals:

[0020] Working surface 1,

[0021] Overburden stratum 2, target layer 21, mudstone layer 22, siltstone layer 23,

[0022] The first mining tunnel 31, the second mining tunnel 32, the pressure relief tunnel 4,

[0023] Pressure relief hole 5, first pressure relief hole 51, end hole position 511 of the first pressure relief hole, second pressure relief hole 52, end hole position 521 of the second pressure relief hole,

[0024] Slit 6, hydraulic fracturing 7. DETAILED DESCRIPTION

[0025] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0026] like Figure 1 As shown, the method for preventing rock bursts in the working face 1 by means of distributed cutting 6 fracturing in the coal seam roof tunnel of the embodiment of the present invention comprises: determining the target layer 21 according to the characteristics of the overlying rock layer 2 of the working face 1, and the working face 1 is formed between the first mining tunnel 31 and the second mining tunnel 32. A pressure relief tunnel 4 is excavated in the target layer 21, and the pressure relief tunnel 4 is along the excavation direction of the working face 1 (such as Figure 2 The pressure relief hole 5 is drilled in the pressure relief tunnel 4 and extends in the inclination direction of the working face 1 (as shown in the front and rear direction) and is located between the first recovery tunnel 31 and the second recovery tunnel 32. Figure 3The hydraulic fracturing 7 is performed in the pressure relief hole 5 to cover the preset range on both sides of at least one mining road in its inclination direction.

[0027] Specifically, Figure 2 and Figure 3 As shown, the first mining tunnel 31 is located on the left, the second mining tunnel 32 is located on the right, and a working face 1 is formed between the first mining tunnel 31 and the second mining tunnel 32. By arranging the pressure relief tunnel 4 between the first mining tunnel 31 and the second mining tunnel 32 in the horizontal direction, it is convenient to drill holes in the areas above the first mining tunnel 31 and the second mining tunnel 32 at the same time through the pressure relief tunnel 4.

[0028] The characteristics of the overlying rock stratum 2 on the working face 1 can be obtained through the drilling column chart. The drilling column chart can clearly display the lithology, thickness and other information of the rock stratum, which is convenient for determining the characteristics of the overlying rock stratum 2 on the working face 1, and then determining the target layer 21. It can be understood that the target layer 21 is a thick and hard rock layer in the overlying rock stratum 2 on the working face 1, and the height of the pressure relief tunnel 4 is determined according to the height of the target layer 21, for example, it is set at the lower part of the target layer 21 near the middle position in the up and down directions.

[0029] like Figure 3 As shown, the mudstone layer 22 and the siltstone layer 23 are located above the coal seam from bottom to top, wherein the thickness of the mudstone layer 22 is 4.3 m, and the thickness of the siltstone layer 23 is 10.2 m. Since the lithology of the mudstone layer 22 is relatively soft and the lithology of the siltstone layer 23 is relatively hard, the mudstone layer 22 is easy to break during the mining process of the working face 1, and the siltstone layer 23 forms a suspended roof structure during the mining process of the working face 1, which is difficult to break in time. The stress state of the rock mass around the mining roadway changes, resulting in stress concentration, and the stability of the mining roadway is difficult to ensure. In other words, the siltstone layer 23 above the coal seam is the key layer, that is, the target layer 21 in this embodiment.

[0030] Optionally, the pressure relief tunnel 4 is arranged in the middle of the first mining tunnel 31 and the second mining tunnel 32, and the pressure relief tunnel 4 is located in the target layer 21 above the working face 1. For example, the working face 1 has a dip length of 150m, that is, the distance between the two mining tunnels is 150m, the pressure relief tunnel 4 is arranged at a distance of 75m from the first mining tunnel, and the pressure relief tunnel 4 is arranged approximately 9m above the coal seam to fracture the siltstone layer 23.

[0031] For example, the pressure relief tunnel 4 is 3m high and 4m wide, and the length of the pressure relief tunnel 4 is the same as the length of the first recovery tunnel 31 and the second recovery tunnel 32. In this embodiment, the specific width and height of the pressure relief tunnel 4 are not limited, and as long as the size that can be used to drill the target layer 21 in the pressure relief tunnel 4 is within the protection scope of this embodiment.

[0032] In the embodiment of the present invention, a pressure relief tunnel 4 is excavated in the thick hard rock layer in the overlying rock layer 2 of the working face 1, pressure relief holes 5 are formed by drilling holes in the pressure relief tunnel 4 in the directions of the first recovery tunnel 31 and the second recovery tunnel 32, and hydraulic fracturing 7 is performed in the pressure relief holes 5. Since the present embodiment performs transverse drilling and hydraulic fracturing in the thick hard roof, the stress level of the overlying rock layer 2 of the first recovery tunnel 31 and the second recovery tunnel 32 can be effectively reduced, and the stability of the first recovery tunnel 31 and the second recovery tunnel 32 can be improved.

[0033] The embodiment of the present invention pre-expels a pressure relief tunnel 4 in the target layer 21 overlying the roof of the working face 1, and implements dense cutting 6 and fracturing in the pressure relief hole 5, which is beneficial to the continuous fracturing of the thick and hard roof and avoids the mutual interference of the mining and pressure relief processes, and reduces the original rock stress and structural stress level of the tunnel in the area to be mined in advance, so as to realize the smooth mining of the working face 1 in the low stress area, thereby greatly reducing the stress concentration and impact risk during the mining of the working face 1.

[0034] Furthermore, in this embodiment, a pressure relief tunnel 4 is excavated in advance in the target layer 21 in the overlying rock stratum 2 of the working face 1, and the thick hard roof on the mining tunnel of the working face 1 of the impact ground pressure coal seam to be mined is densely fractured in the pressure relief tunnel 4. The thick hard roof is weakened and transformed as a whole, and the mining tunnel within the fracturing coverage range is in a low stress zone, so that the tunnel is in a protected state during the mining of the working face 1, thereby effectively reducing the impact risk.

[0035] In some embodiments, drilling is performed in the pressure relief tunnel 4 to form pressure relief holes 5, including: determining the number of pressure relief holes 5 in each row according to the thickness of the target layer 21, each row of pressure relief holes 5 including at least one first pressure relief hole 51 and at least one second pressure relief hole 52, the first pressure relief holes 51 and the second pressure relief holes 52 being relatively arranged in the inclination direction of the working face 1; determining the spacing distance between two adjacent rows of pressure relief holes 5 in the excavation direction of the working face 1 according to the scope of the hydraulic fracturing 7; and drilling multiple pressure relief holes 5 in each row of pressure relief holes 5 using a drilling site, and drilling multiple rows of pressure relief holes 5 according to the spacing distance between two adjacent rows of pressure relief holes 5.

[0036] Specifically, Figure 3 As shown, the first pressure relief hole 51 is located on the left side, and the second pressure relief hole 52 is located on the right side, that is, the first pressure relief hole 51 is formed by drilling from the left side of the tunnel to the left, and the second pressure relief hole 52 is formed by drilling from the right side of the tunnel to the right.

[0037] In this embodiment, the number of pressure relief holes 5 in each row is determined according to the thickness of the target layer 21 to ensure that the fracturing range of each row of pressure relief holes 5 can cover the target layer 21 in the up and down directions. The spacing distance of multiple rows of pressure relief holes 5 in the front-to-back direction is determined according to the distance of the hydraulic fracturing range 7 in the front-to-back direction to ensure that the pressure range of multiple rows of pressure relief holes 5 covers the target layer 21 in the front-to-back direction, thereby ensuring the fracturing effect.

[0038] In some embodiments, a drilling site is used to drill multiple pressure relief holes 5 in each row of pressure relief holes 5, including: drilling at one end of the pressure relief tunnel 4 to form at least one first pressure relief hole 51, the first pressure relief hole 51 extends along the inclination direction of the working face 1 and is arranged upwardly inclined, and the final hole position 511 of the first pressure relief hole is located on the side of the first mining tunnel 31 away from the second mining tunnel 32; drilling at the other end of the pressure relief tunnel 4 to form at least one second pressure relief hole 52, the second pressure relief hole 52 extends along the inclination direction of the working face 1 and is arranged upwardly inclined, and the final hole position 521 of the second pressure relief hole is located on the side of the second mining tunnel 32 away from the first mining tunnel 31.

[0039] Specifically, Figure 3 As shown, the first pressure relief hole 51 extends in the left-right direction and is arranged obliquely to the upper left, and the terminal hole position 511 of the first pressure relief hole is located on the left side of the first recovery tunnel 31. The second pressure relief hole 52 extends in the left-right direction and is arranged obliquely to the upper right, and the terminal hole position 521 of the second pressure relief hole is located on the right side of the second recovery tunnel 32. By limiting the terminal hole positions 521 of the first pressure relief hole 51 and the second pressure relief hole, it is ensured that when the first pressure relief hole 51 and the second pressure relief hole 52 are hydraulically fractured 7, the hydraulic fracturing range 7 covers the first recovery tunnel 31 and the second recovery tunnel 32 in the left-right direction, thereby ensuring the fracturing effect.

[0040] In some embodiments, the horizontal distance A between the end hole position 511 of the first pressure relief hole and the end of the first mining tunnel 31 away from the second mining tunnel 32 is 15-20m. By limiting the horizontal distance between the end hole position 511 of the first pressure relief hole and the left end of the first mining tunnel 31, it is ensured that the hydraulic fracturing 7 range in the first pressure relief hole 51 covers the first mining tunnel 31 in the left and right directions, and the fracturing range covers the mining tunnel, so that the mining tunnel is in a low stress area during the mining of the working face 1, avoiding stress concentration and increasing the risk of impact, thereby improving the stability of the first mining tunnel 31.

[0041] In some embodiments, the horizontal distance A between the end hole position 521 of the second pressure relief hole and the end of the second recovery tunnel 32 away from the first recovery tunnel 31 is 15-20m. By limiting the horizontal distance between the end hole position 521 of the second pressure relief hole and the right end of the second recovery tunnel 32, it is ensured that the hydraulic fracturing 7 range in the second pressure relief hole 52 covers the second recovery tunnel 32 in the left and right directions, thereby improving the stability of the second recovery tunnel 32.

[0042] In some embodiments, when there is one first pressure relief hole 51 in each row of pressure relief holes 5, the final hole position 511 of the first pressure relief hole is located at the middle position of the target layer 21 in the up-down direction, and the angle between the extension direction of the first pressure relief hole 51 and the horizontal plane is B, and 5°≤B≤10°. By setting the first pressure relief hole 51 to extend from right to left and be arranged tilted upward, it is convenient to drill the first pressure relief hole 51.

[0043] In some embodiments, when there is one second pressure relief hole 52 in each row of pressure relief holes 5, the final hole position 521 of the second pressure relief hole is located at the middle position of the target layer 21 in the up-down direction, and the angle between the extension direction of the second pressure relief hole 52 and the horizontal plane is B, and 5°≤B≤10°. By setting the second pressure relief hole 52 to extend from left to right and be arranged upwardly tilted, it is convenient to drill the second pressure relief hole 52.

[0044] In this embodiment, the pressure relief tunnel 4 is located in the lower middle part of the target layer 21, which is convenient for the inclined upward arrangement of the first pressure relief hole 51 and the second pressure relief hole 52. At the same time, the terminal hole position of the pressure relief hole 5 is set in the middle position of the target layer 21, which is convenient for the distribution of the fracturing range in the upper and lower directions when hydraulic fracturing 7 is performed in the pressure relief hole 5, ensuring that the hydraulic fracturing 7 range covers the target layer 21 in the upper and lower directions.

[0045] Optionally, B is 5°.

[0046] In some embodiments, when there are multiple first pressure relief holes 51 in each row of pressure relief holes 5 , the multiple first pressure relief holes 51 are arranged at intervals in the up-and-down direction.

[0047] In some embodiments, when there are multiple second pressure relief holes 52 in each row of pressure relief holes 5 , the multiple second pressure relief holes 52 are arranged at intervals in the up-down direction.

[0048] It can be understood that, when the thickness of the target layer 21 is greater, the number of pressure relief holes 5 arranged at intervals in the up and down directions in each row of pressure relief holes 5 is greater, and when the thickness of the target layer 21 is smaller, the number of pressure relief holes 5 arranged at intervals in the up and down directions in each row of pressure relief holes 5 is smaller, and the minimum number is one.

[0049] In this embodiment, a plurality of pressure relief holes 5 spaced apart in the vertical direction are provided in each row of pressure relief holes 5 to ensure that when hydraulic fracturing 7 is performed in the plurality of pressure relief holes 5 , the fracturing range covers the target layer 21 in the vertical direction.

[0050] In some embodiments, before performing hydraulic fracturing 7 in the pressure relief hole 5 to cover a preset range on both sides of at least one mining tunnel in its inclination direction, the method also includes: cutting 6 on the pressure relief hole 5, the direction of the cutting 6 extending along the excavation direction of the working face 1, and / or the direction of the cutting 6 extending along the up and down direction.

[0051] Specifically, the direction of the slit 6 may extend in the front-to-back direction, or the direction of the slit 6 may extend in the up-down direction, or the direction of the slit 6 of a portion of the slit 6 may extend in the front-to-back direction, and the direction of the other portion of the slit 6 may extend in the up-down direction. In this embodiment, by cutting the slit 6 in the pressure relief hole 5 before the hydraulic fracturing 7, directional cracks are generated during the hydraulic fracturing 7, thereby improving the fracturing effect on the target layer 21 above the mining roadway.

[0052] When cutting 6 in the pressure relief hole 5, the cutting 6 at the next position is carried out after the fracturing of the cutting 6 at the previous position, until the pre-cracking of the overlying roof of the roadway in the area to be mined is completed. By pre-excavating the pressure relief roadway 4 in the roof of the working face 1 in the area to be mined, intensive cutting 6 and fracturing are carried out on the overlying thick hard roof in the pressure relief roadway 4, and the original rock stress and structural stress level in the mining roadway area are reduced in advance, so that the mining roadway can be used safely in the low stress area, thereby greatly reducing the stress concentration and impact risk during the mining of the working face 1.

[0053] In some embodiments, slitting 6 is performed on the pressure relief hole 5, comprising: using a slitting 6 device to perform slitting 6 at a position that is a first preset distance away from the final hole position of the pressure relief hole 5; and moving the slitting 6 device back a second preset distance and continuing to perform slitting 6 until the slitting 6 position is located between the first mining tunnel 31 and the second mining tunnel 32, and the horizontal distance between the slitting 6 position and the first mining tunnel 31 and / or the second mining tunnel 32 is greater than a third preset distance.

[0054] Specifically, since the hydraulic fracturing 7 after slitting 6 has a certain fracturing range in the left and right directions, by performing slitting 6 at a position at a first preset distance from the end hole position of the pressure relief hole 5, it can be ensured that the hydraulic fracturing 7 after slitting 6 covers the end hole position of the pressure relief hole 5.

[0055] The slits 6 are cut in sequence from the terminal hole position 511 of the first pressure relief hole toward the hole mouth of the first pressure relief hole 51 until the horizontal distance between the slit 6 position and the first mining tunnel 31 is greater than the third preset distance, and the slit 6 position is located between the first mining tunnel 31 and the second mining tunnel 32, then the slit 6 is stopped and the first pressure relief hole 51 is hydraulically fractured 7 to ensure that the range of the hydraulic fracture 7 covers the preset distance on both sides of the first pressure relief hole 51 in the left and right directions.

[0056] Cutting 6 is performed sequentially from the end hole position 521 of the second pressure relief hole toward the hole mouth of the first pressure relief hole 51 until the horizontal distance between the cutting 6 position and the second mining tunnel 32 is greater than the third preset distance, and the cutting 6 position is located between the first mining tunnel 31 and the second mining tunnel 32, then the cutting 6 is stopped and hydraulic fracturing 7 is performed on the first pressure relief hole 51 to ensure that the range of the hydraulic fracturing 7 covers the preset distance on both sides of the second pressure relief hole 52 in the left and right directions.

[0057] For example, the first preset distance is 5 m, the second preset distance is 7 m, and the third preset distance is 15-20 m.

[0058] In some embodiments, the length of the slit 6 is 0.5-1 m. By limiting the length of the slit 6, it is avoided that the length of the slit 6 is too small, which makes it difficult to ensure the fracturing effect, and the length of the slit 6 is too large, which increases the difficulty of construction.

[0059] Optionally, the length of the slit 6 is 0.5 m.

[0060] In some embodiments, after hydraulic fracturing 7 is performed in the pressure relief hole 5 , the method further includes: recovering the working face 1 .

[0061] Specifically, according to the borehole column chart, the thick hard sandstone layer above the working face 1 is determined as the target layer 21 for fracturing the cutting seam 6, and the pressure relief tunnel 4 is excavated in the target layer 21 just above the middle of the working face 1. According to the thickness of the target layer 21, a drilling site is set up in a section of the pressure relief tunnel 4, and a borehole is drilled on each side of the drilling site with a depth of 100m to cover 15m outside the mining tunnel. A horizontal cutting seam 6 with a grinding jet is used at 5m from the bottom of the hole. The length of the cutting seam 6 is 0.5m, and hydraulic fracturing 7 is carried out at the cutting seam 6. The cutting 6 device is retreated by 7m, and the horizontal cutting 6 length is cut again by 0.5m, and hydraulic fracturing 7 is carried out at the cutting 6 until the cutting 6 is fractured to 15m inside the mining roadway, ensuring that the cutting 6 fracturing can cover the peak area of ​​the mining roadway support pressure, and the mining roadways are all in the horizontal projection area of ​​the cutting 6 fracturing section, so that the mining roadways are all in the coverage of the cutting 6 fracturing; the drilling site spacing is set to 10m to ensure that the cracks formed by adjacent cutting 6 fracturing holes can be connected to each other to avoid the formation of pre-fracture blind areas. After the pressure relief roadway 4 is implemented, the deep hole cutting 6 fracturing is carried out on both sides of the pressure relief roadway 4 in a backward manner to achieve the overall weakening of the thick hard roof, and ensure that the pre-fracture range of the roof covers the mining roadway of the working face 1. After the cutting 6 fracturing at the previous position is implemented, the cutting 6 fracturing at the next position is carried out until the pre-fracture work of the roof overlying all the roadways to be mined is completed. After the fracturing of the thick hard roof cutting 6 on the mining face 1 tunnel is completed, the mining of the impact ground pressure coal seam working face 1 is carried out, and the mining tunnel is in a low stress area until the mining of the working face 1 is completed.

[0062] In this embodiment, the target layer 21 is determined by the characteristics of the overlying rock layer 2 on the working face 1, and the position of the pressure relief tunnel 4 is determined according to the thickness of the target layer 21 and the horizontal distance between the first mining tunnel 31 and the second mining tunnel 32, so that the pressure relief tunnel 4 is set in the middle of the first mining tunnel 31 and the second mining tunnel 32 and is located in the middle and lower part of the target layer 21. By drilling holes to the left and right in the pressure relief tunnel 4 to form pressure relief holes 5 and passing the mining tunnel, and then cutting 6 in the pressure relief hole 5 and performing horizontal fracturing, the hydraulic fracturing 7 is ensured. The range is expanded in the up-down direction to the size of the target layer 21 in the up-down direction, and the range of the hydraulic fracturing 7 is expanded in the left-right direction to the 15m range on both sides of the mining roadway. The range of the hydraulic fracturing 7 of the two adjacent pressure relief holes 5 is connected to avoid the existence of a fracturing blind spot, realize the overall weakening of the thick and hard roof above the mining roadway, and ensure that the pre-cracking range of the roof covers the areas on both sides of the mining roadway. After the fracturing of the thick and hard roof cutting 6 above the mining area roadway is completed, the impact ground pressure coal seam mining is carried out, and the mining roadway is within the coverage range of the fracturing of the overlying roof cutting 6 until the mining of the working face 1 is completed.

[0063] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0064] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0065] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0066] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0067] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0068] It is to be understood that the above embodiments are exemplary and are not to be construed as limiting the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A method for preventing and controlling rock burst at a working surface by distributed fracturing in a coal seam roof tunnel, characterized in that: include: Determining a target layer according to the characteristics of the overlying strata on a working face, wherein the working face is formed between a first mining tunnel and a second mining tunnel; Excavating a pressure relief tunnel in the target layer, wherein the pressure relief tunnel extends along the excavation direction of the working face and is located between the first mining tunnel and the second mining tunnel; Drilling in the pressure relief tunnel to form a pressure relief hole, wherein the pressure relief hole extends along the inclination direction of the working face and passes through the target layer above the mining tunnel; Hydraulic fracturing is performed in the pressure relief hole to cover a preset range on both sides of at least one of the recovery tunnels in its inclination direction.

2. The method for preventing and controlling rock burst at the working face by distributed slit fracturing in the coal seam roof tunnel according to claim 1, characterized in that: Drilling a hole in the pressure relief tunnel to form a pressure relief hole comprises: Determine the number of each row of pressure relief holes according to the thickness of the target layer, each row of pressure relief holes includes at least one first pressure relief hole and at least one second pressure relief hole, and the first pressure relief hole and the second pressure relief hole are arranged opposite to each other in the inclination direction of the working surface; Determining the spacing between two adjacent rows of pressure relief holes in the excavation direction of the working face according to the scope of the hydraulic fracturing; A drilling site is used to drill multiple pressure relief holes in each row of pressure relief holes, and multiple rows of pressure relief holes are drilled according to the interval distance between two adjacent rows of pressure relief holes.

3. The method for preventing and controlling rock burst at the working face by distributed slit fracturing in a coal seam roof tunnel according to claim 2, characterized in that: Use the drilling site to drill multiple pressure relief holes in each row of pressure relief holes, including: Drilling at one end of the pressure relief tunnel to form at least one first pressure relief hole, the first pressure relief hole extending along the inclination direction of the working face and arranged obliquely upward, the terminal hole position of the first pressure relief hole being located on a side of the first recovery tunnel away from the second recovery tunnel; At least one second pressure relief hole is drilled at the other end of the pressure relief tunnel, the second pressure relief hole extends along the inclination direction of the working face and is arranged upwardly inclined, and the terminal hole position of the second pressure relief hole is located on the side of the second mining tunnel away from the first mining tunnel.

4. The method for preventing and controlling rock burst at the working face by distributed cutting and fracturing in the coal seam roof tunnel according to claim 3 is characterized in that: The horizontal distance A between the final hole position of the first pressure relief hole and the end of the first mining tunnel away from the second mining tunnel is 15-20m; and / or, The horizontal distance A between the final hole position of the second pressure relief hole and the end of the second mining tunnel away from the first mining tunnel is 15-20m.

5. The method for preventing and controlling rock burst at the working face by distributed cutting and fracturing in the coal seam roof tunnel according to claim 4, characterized in that: When there is one first pressure relief hole in each row of pressure relief holes, the terminal hole position of the first pressure relief hole is located in the middle position of the target layer in the up-down direction, the angle between the extension direction of the first pressure relief hole and the horizontal plane is B, and 5°≤B≤10°; and / or, When there is one second pressure relief hole in each row of pressure relief holes, the terminal hole position of the second pressure relief hole is located in the middle position of the target layer in the up and down directions, and the angle between the extension direction of the second pressure relief hole and the horizontal plane is B, and 5°≤B≤10°.

6. The method for preventing and controlling rock burst at the working face by distributed cutting and fracturing in the coal seam roof tunnel according to claim 4, characterized in that: When there are a plurality of first pressure relief holes in each row of pressure relief holes, the plurality of first pressure relief holes are arranged at intervals in the vertical direction, and / or, When there are a plurality of second pressure relief holes in each row of pressure relief holes, the plurality of second pressure relief holes are arranged at intervals in the up-down direction.

7. The method for preventing and controlling rock burst at the working face by distributed slit fracturing in a coal seam roof tunnel according to claim 5, characterized in that: Before hydraulic fracturing is performed in the pressure relief hole to cover a preset range on both sides of at least one of the recovery tunnels in its inclination direction, the method further comprises: The pressure relief hole is cut into slits, wherein the cutting direction extends along the excavation direction of the working face, and / or the cutting direction extends along the up-down direction.

8. The method for preventing and controlling rock burst at the working face by distributed cutting and fracturing in the coal seam roof tunnel according to claim 7, characterized in that: The pressure relief hole is cut, comprising: Using a slitting device to slit a position spaced a first preset distance from the final hole position of the pressure relief hole; The slitting device is retreated a second preset distance and slitting is continued until the slitting position is between the first mining tunnel and the second mining tunnel, and the horizontal distance between the slitting position and the first mining tunnel and / or the second mining tunnel is greater than a third preset distance.

9. The method for preventing and controlling rock burst at the working face by distributed slit fracturing in a coal seam roof tunnel according to claim 8, characterized in that: The length of the slit is 0.5-1m.

10. The method for preventing and controlling rock burst at the working face by distributed cutting and fracturing in the coal seam roof tunnel according to claim 1, characterized in that: After hydraulic fracturing is performed in the pressure relief hole, the method further comprises: recovering the working face.

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