A method and device for pressure relief and outburst elimination of coal seams

Abstract

The present invention discloses a method and device for pressure relief and outburst elimination of coal seams, belonging to the technical field of pressure relief and outburst elimination of coal seams. This method realizes outburst elimination of coal seams by using a wire saw to cut seams in the coal seam, relieve pressure, enhance permeability, and discharge gas. The device for pressure relief and outburst elimination of coal seams includes a drill rig and a wire saw machine with a wire saw. Four boreholes are drilled in the coal and rock mass in front of the coal uncovering working face by using the drill rig, and it is ensured that the control range of the four boreholes is greater than the first control distance outside the outline of the coal uncovering roadway, and the minimum distance from the outer edge of the control range of the four boreholes to the outline of the coal uncovering roadway is not less than the second control distance. The wire saw machine cuts and connects the boreholes based on the boreholes to form a target space. Among them, the wire saw machine first cuts the top surface and two side surfaces of the target space by using the reverse cutting method and then cuts the target space for pressure relief and permeability enhancement by using the nested cutting method; the angle of the borehole is determined based on the occurrence conditions of the coal seam. The present invention improves the coal seam extraction efficiency, with low cost and high efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of coal seam pressure relief and outburst elimination, and in particular relates to a method and device for coal seam pressure relief and outburst elimination. Background Art

[0002] As coal mining gradually extends to deeper areas, the ground stress and gas pressure further increase, and the risk of coal and gas outburst disasters continues to increase, especially the high risk of outburst during the stone gate coal mining process, which seriously restricts the safe and efficient mining of deep coal resources. Coal and gas outburst is basically the result of the combined effects of ground stress, gas pressure and the physical properties of coal and rock.

[0003] At present, the anti-blowout measures of Shimen coal mining working face mainly include pre-extraction of gas and discharge drilling to reduce gas pressure; hydraulic measures such as hydraulic cutting and punching to relieve pressure and increase permeability of coal seams; metal skeletons, coal body solidification and other measures to improve the hardness of coal rock mass. Although the above measures have achieved the effect of eliminating coal seam blowouts, it takes a long time to drain gas through drilling, and the costs of hydraulic cutting, punching and installation of metal skeletons are relatively high.

[0004] Therefore, there is an urgent need for new coal mining and coal outburst prevention technologies that can economically and efficiently solve the problem of coal and gas outbursts during coal mining in mines.

[0005] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0006] In order to solve the technical problems that the existing technology has achieved the effect of eliminating coal seam outbursts, but the extraction and drainage of gas through drilling holes takes a long time, and the measures such as hydraulic cutting, punching and installation of metal frames are costly, a method and device for decompressing and eliminating coal seam outbursts is provided.

[0007] In a first aspect, the present invention provides a method for decompressing and eliminating coal seam outbursts, comprising the following steps:

[0008] Use a drilling rig to configure four boreholes on the coal seam, and ensure that the control range of the four boreholes is greater than the first control distance outside the coal mining tunnel contour line, and the minimum distance from the outer edge of the control range of the four boreholes to the coal mining tunnel contour line is not less than the second control distance; the angle of the boreholes in the coal seam is determined based on the coal seam occurrence, and the coal seam occurrence includes the direction, dip, inclination and thickness of the coal seam, and the coal seam occurrence is explored by conducting geological drilling in the coal seam in the extraction tunnel;

[0009] A wire saw machine with a wire saw is used to cut out a target space connected to the coal seam borehole based on the borehole in the coal seam, wherein the wire saw machine first uses a reverse cutting method to cut out the top surface and two side surfaces of the target space and then uses a sleeve cutting method to cut out the target space for pressure relief and permeability enhancement.

[0010] In some embodiments, the specific steps of cutting out the top surface and two surfaces of the target space by the reverse cutting method include:

[0011] First, adjusting the angles of the corresponding two sets of wire saw positioning guides so that the central planes of the two sets of wire saw positioning guides are parallel to the plane of the target space;

[0012] Then the wire saw is passed around the two wire saw positioning guide parts, and the wire saw and the two wire saw positioning guide parts are pushed into the corresponding boreholes by using the corresponding position adjustment parts, and fixed at the pre-cutting point, and the wire saw is connected to the two wire saw movement direction adjustment parts, the two wire saw tensioning parts and the wire saw machine;

[0013] Then determine the reverse switching circuit;

[0014] Finally, the wire saw machine is started to cut the coal seam at a uniform speed. At the same time, through the backward movement of the wire saw machine and the coordination of the wire saw tensioning part, the wire saw is kept tensioned and continuous forward cutting is achieved to complete the reverse cutting process.

[0015] In some embodiments, the reverse cutting circuit is in the following order: a rope saw machine, a group of rope saw tensioning parts, a group of rope saw movement direction adjustment parts, a group of rope saw positioning guide parts, a rock mass at one point, another rock mass at another point, another group of rope saw positioning guide parts, another group of rope saw movement direction adjustment parts, another group of rope saw tensioning parts, and a rope saw machine.

[0016] In some embodiments, before cutting, the wire saw needs to be in a pre-tensioned state by adjusting the wire saw tensioning part and the position of the wire saw machine.

[0017] In some embodiments, after the rope saw cuts beyond the coal seam, the rope saw is retracted along the original path, the rope saw is kept in a tensioned state, the rope saw machine is retracted, and the rope saw cuts out of the rock mass to the tunnel working surface, and then the speed is reduced and the rope is retracted to prepare for the next cutting.

[0018] In some embodiments, cutting out the target space for pressure relief and anti-reflection by using the sleeve cutting method includes:

[0019] Step S341, winding the rope saw around the positioning guide wheel 5a, the positioning guide wheel 5b, the positioning guide wheel 5c, and the positioning guide wheel 5d at the same time, adjusting the center planes of the positioning guide wheels 5a and 5d in the boreholes aA and dD to be parallel to the side AadD, and the center planes of the positioning guide wheels 5b and 5c in the boreholes bB and cC to be parallel to the side BbcC, and keeping the rope saw taut;

[0020] Step S342: Using the hydraulic telescopic rods 6a, 6b, 6c, and 6d and moving the wire saw machine, slowly push the four positioning guide wheels 5a, 5b, 5c, and 5d to the pre-cut surface ABCD, so that the distal ends of the four positioning guide wheels 5a, 5b, 5c, and 5d are in the same plane as the pre-cut surface ABCD. Then, retract the hydraulic telescopic rods 6a and 6b in the drill holes aA and bB to withdraw the upper two positioning guide wheels 5a and 5b. At this time, the rope sleeving operation is completed;

[0021] Step S343: Connect the outer end of the wire saw to the rotary wheels 4d, 4c, tensioning wheels 3d, and 3c at the bottom surface DdcC and connect the wire saw machine;

[0022] Step S344: Determine the sleeving cutting circuit. The sleeving cutting circuit is in sequence: wire saw machine, tensioning wheel 3d, rotary wheel 4d, positioning guide wheel 5d, coal and rock mass at point A, coal and rock mass at point B, positioning guide wheel 5c, rotary wheel 4c, tensioning wheel 3c, wire saw machine;

[0023] Step S345: Before sleeving and cutting, it is also necessary to adjust the positions of the tensioning wheels 3d, 3c, and the wire saw machine to make the wire saw in a pre-tensioned state to prevent the rope from coming off;

[0024] Step S346: Turn on the wire saw machine and cut the coal and rock mass at a uniform speed. Through the backward movement of the wire saw machine and coordinating the tensioning wheels 3d and 3c, the wire saw is continuously tightened to achieve cutting from top to bottom;

[0025] Step S347: When the wire saw cuts to the connection line at the lower ends of the two positioning guide wheels 5d and 5c in the drill holes cC and dD, the positioning guide wheels in the drill holes lose their function, and the two rotary wheels 4d and 4c at the outlets of the drill holes cC and dD act as positioning guide wheels;

[0026] Step S348: At this time, when the wire saw retracts the rope and still maintains the cutting state, the wire saw is in a tensioned state, and the wire saw machine is retracted to prevent the rope from coming off;

[0027] Step S349: The wire saw winds around and cuts from the bottom surface DdcC position to the working face of the crossheading roadway, and the rope is retracted at a reduced speed;

[0028] Among them, the rotary wheel is the wire saw movement direction adjustment part, the tensioning wheel is the wire saw tensioning part, the positioning guide wheel is the wire saw positioning and guiding part, and the hydraulic telescopic rod is the position adjustment part.

[0029] In some embodiments, the method of using the sleeving cutting method to cut out the pressure relief and permeability enhancement target space further includes:

[0030] Repeat the steps S341 to S349, and control the position of the slot cut inside the coal seam by shortening the advancing distance of the four sets of rope saw positioning guide parts, cut the coal seam multiple times from far to near, and inspect the effect of the coal seam after multiple cuttings, and highlight that the maximum expansion deformation of the unloaded coal seam in the mine is greater than 0.3%, which meets the requirements of unloading and permeability enhancement;

[0031] By monitoring the subsidence of the upper boundary of the coal seam, Q 1 and the expansion of the lower boundary Q 2 , to calculate the maximum expansion deformation rate ζ of the coal body, the determination formula is:

[0032]

[0033] H represents the original thickness of the coal seam; h represents the width of the slot (the diameter of the rope saw); and n represents the number of cuts.

[0034] In a second aspect, the present invention provides a coal seam pressure relief and outburst elimination device, which is applicable to any one of the coal seam pressure relief and outburst elimination methods described in the first aspect, and the coal seam pressure relief and outburst elimination device comprises:

[0035] A drilling machine is arranged before the minimum normal distance between the coal mining working face and the coal seam; the drilling machine is configured with four boreholes on the coal seam, and ensures that the control range of the four boreholes is greater than the first control distance outside the contour line of the coal mining roadway, and the minimum distance from the outer edge of the control range of the four boreholes to the contour line of the coal mining roadway is not less than the second control distance;

[0036] A wire saw machine with a wire saw cuts out a target space connected to the coal seam borehole based on the borehole in the coal seam, wherein the wire saw machine first cuts out the top surface and two side surfaces of the target space of the coal seam borehole by a reverse cutting method through the wire saw and then cuts out the target space for pressure relief and permeability enhancement by a sleeve cutting method;

[0037] The angle of the drilling hole in the coal seam is determined based on the occurrence of the coal seam, and the occurrence of the coal seam includes the direction, dip, inclination and thickness of the coal seam. The occurrence of the coal seam is explored by conducting geological drilling into the coal seam in the extraction lane.

[0038] In some embodiments, the wire saw machine is a diamond bead wire saw machine.

[0039] In some embodiments, the coal seam pressure relief and outburst elimination device further comprises:

[0040] A wire saw traction unit, arranged on the wire saw machine and connected to the wire saw, for driving the wire saw to run along a cutting track;

[0041] Four or more rope saw movement direction adjustment parts, which are arranged on the rope saw machine and connected to the rope saw, and are used to adjust the movement direction of the rope saw;

[0042] More than four wire saw tensioning parts, connected to the wire saw for adjusting the tension of the wire saw;

[0043] More than four wire saw positioning and guiding parts, connected to the wire saw for fixing the movement track of the wire saw;

[0044] A position adjusting part, connected to the more than four wire saw tensioning parts and the more than four wire saw positioning and guiding parts for adjusting the positions of the more than four wire saw tensioning parts and the more than four wire saw positioning and guiding parts; the position adjusting part is electrically connected to the wire saw machine, so that the action of the position adjusting part is controlled by the wire saw machine.

[0045] Compared with the prior art, the technical effects achieved by the present invention are as follows:

[0046] The present invention can perform positioning cutting on the coal seam. The wire saw slotting pressure relief and permeability enhancement technology can continuously cut slots inside the coal seam and has a large cutting range. Often, the purpose of stress release can be achieved through several cuts, realizing the purpose of large-area permeability enhancement of the coal seam; at the same time, the wire saw cutting process has a strong water-carrying capacity. These waters can moisten the coal and rock mass, weaken the brittleness of the coal and rock mass, increase its plasticity, and reduce its elastic energy. In addition, the water brought into the coal body during the nested cutting process can reduce the desorption rate of the remaining gas in the coal body after wetting the coal body, reducing the gas expansion energy; according to the requirements of outburst prevention during cross-measurement roadway uncovering of coal seams, the control range of the cross-cut boreholes is often larger than the outline of the roadway at the coal uncovering location. Therefore, the coal seam rock mass cut by the present invention presents a "large inside and small outside" shape feature and still retains the protective effect of the safety rock pillar, providing a barrier to prevent the outburst energy of gas; multiple cuts and multiple slots are made on the coal seam, and the cut coal chips are removed by adjusting the cutting direction of the wire saw and its water-carrying capacity, providing conditions for the expansion and deformation of the coal seam. The present invention has a fast construction speed, low cost, safety and high efficiency, and solves the technical problems in the prior art that although the outburst elimination effect on the coal seam is achieved, the time-consuming for discharging gas by the drainage boreholes is long, and the costs of measures such as hydraulic slotting, punching, and installing metal skeletons are high. Description of the Drawings

[0047] Figure 1 is a working schematic diagram of the coal seam pressure relief and outburst elimination device provided by the present invention in an embodiment;

[0048] Figure 2 is a working schematic diagram of the coal seam pressure relief and outburst elimination device provided by the present invention in a first perspective;

[0049] Figure 3 is a working schematic diagram of the coal seam pressure relief and outburst elimination device provided by the present invention in a second perspective;

[0050] Figure 4It is a working schematic diagram of the coal seam pressure relief and outburst elimination device provided in an embodiment of the present invention from the third perspective;

[0051] Figure 5 It is a structural schematic diagram of the support frame and its associated parts provided in an embodiment of the present invention. Detailed implementation manners

[0052] The technical solutions of the present invention will be described below through specific embodiments with reference to the accompanying drawings. It should be understood that one or more than four steps mentioned in the present invention do not exclude the existence of other methods and steps before and after the combined steps, or other methods and steps can be inserted between these clearly mentioned steps. It should also be understood that these examples are only used to illustrate the present invention and not to limit the scope of the present invention. Unless otherwise specified, the numbers of each method step are only for the purpose of identifying each method step, rather than limiting the arrangement order of each method or limiting the implementation scope of the present invention. The change or adjustment of their relative relationship can also be regarded as the scope in which the present invention can be implemented under the condition of no substantial change in technical content.

[0053] There is no specific limitation on the sources of the raw materials and instruments used in the embodiments, and they can be purchased in the market or prepared according to the conventional methods well-known to those skilled in the art.

[0054] Embodiment:

[0055] The present invention provides a coal seam pressure relief and outburst elimination method and device. The present invention has the advantages of fast construction speed, low cost, safety and high efficiency, and solves the technical problems in the prior art that although the outburst elimination effect on the coal seam is achieved, the time-consuming for gas drainage through drainage boreholes is long, and the costs of measures such as hydraulic slotting, punching and installing metal skeletons are high.

[0056] As Figures 1-5 shown, in some embodiments, a coal seam pressure relief and outburst elimination method is provided, and a coal seam pressure relief and outburst elimination device is adopted in the implementation process of the coal seam pressure relief and outburst elimination method.

[0057] The coal seam pressure relief and outburst elimination device includes: a drill and a wire saw machine 1 with a wire saw. In some embodiments, the wire saw machine 1 is a diamond bead wire saw machine. During the cutting process of the diamond bead wire saw, the disturbance to the coal body is small, which can effectively reduce the damage to the coal seam rock mass, ensure its integrity, maintain the better mechanical stability and bearing capacity of the coal and rock mass, is not easy to collapse the hole, and ensure the integrity of the entire safety rock pillar.

[0058] In some embodiments, the coal seam pressure relief and outburst elimination device further includes: a wire saw traction part 2, a wire saw movement direction adjustment part, a wire saw tensioning part, a wire saw positioning and guiding part, and a position adjustment part.

[0059] The wire saw traction part 2 is arranged on the wire saw machine 1 and connected to the wire saw 8 to drive the wire saw 8 to run along the cutting track;

[0060] The number of the rope saw movement direction adjusting parts is more than four and all are arranged on the rope saw machine 1 and connected to the rope saw 8, so as to adjust the movement direction of the rope saw 8; in some embodiments, the rope saw 8 movement direction adjusting parts are rotating wheels and the number is four;

[0061] The number of the rope saw tensioning parts is more than four and all are connected to the rope saw 8 to adjust the tightness of the rope saw 8; in some embodiments, the rope saw tensioning parts are tensioning wheels and the number is four;

[0062] The number of the rope saw positioning guide parts is more than four and all are connected to the rope saw 8 to fix the movement trajectory of the rope saw 8; in some embodiments, the rope saw positioning guide parts are positioning guide wheels and the number is four;

[0063] The position adjustment part is connected to the four or more rope saw tensioning parts and the four or more rope saw positioning guide parts to adjust the positions of the four or more rope saw tensioning parts and the four or more rope saw positioning guide parts; the position adjustment part is electrically connected to the rope saw machine 1, so that the action of the position adjustment part is controlled by the rope saw machine 1. In some embodiments, the position adjustment part is a hydraulic telescopic rod and the number is four;

[0064] In some embodiments, the coal seam pressure relief and outburst elimination device also includes a support frame, which serves as the base of the entire coal seam pressure relief and outburst elimination device and is used to support the entire coal seam pressure relief and outburst elimination device. The support frame and the axis of the positioning guide wheel are fixed together at the front end of the hydraulic telescopic rod. The length of a single tripod of the support frame is 68 mm. The triangular leg design can maintain the stability of the hydraulic telescopic rod and the positioning guide wheel during rope saw cutting. And it is fixed on both sides of the positioning guide wheel at the same time, and the tripod on the lower inner side is removed to avoid the rope saw from being entangled when the rope is returned during the rope cutting process. Compared with conventional marble mining and cutting technology, the implementation of this method requires the design of the drilling angle and length according to the "Regulations on the Prevention and Control of Coal and Gas Outbursts". Since the drilling length is greater than the marble cutting drilling hole, the hydraulic telescopic rod is often unstable when subjected to force cutting. A triangular support frame is provided on both sides of the guide wheel to prevent the telescopic rod from shaking due to excessive force during cutting, and provide stable support for the positioning guide wheel.

[0065] The coal seam pressure relief and outburst elimination method comprises the following steps:

[0066] Step S1, drilling geological holes in the coal seam in the extraction roadway to find out the coal seam occurrence, which includes the direction, dip and thickness of the coal seam, so as to determine the angle between the roadway and the direction of the coal seam and the angle between the roadway and the dip of the coal seam;

[0067] Step S2. According to the "Regulations on the Prevention and Control of Coal and Gas Outbursts", a certain thickness of safety rock pillar needs to be reserved before the crossheading roadway reaches the coal seam. Drilling rigs should be set up before the minimum normal distance between the coal uncovering working face and the coal seam as required. In some embodiments, the minimum normal distance is 7m. Based on the measured data above and the drilling control area required by the "Regulations on the Prevention and Control of Coal and Gas Outbursts", 4 drill holes are arranged on the coal seam by the drilling rig. The 4 drill holes should ensure that the controlled range of the drill holes is greater than the first control distance outside the outline of the coal uncovering roadway, and the minimum distance from the outer edge of the controlled range to the outline of the roadway (including the outline of the pre-excavated coal uncovering roadway) is not less than the second control distance. In some embodiments, the first control distance is 12m and the second control distance is 5m. The above distances are the safety distances required by the outburst prevention regulations.

[0068] Therefore, determine the angles of the directional drill holes, including: the minimum upward elevation angle of drill hole aA and the minimum leftward deviation angle of the drill hole; the minimum upward elevation angle of drill hole bB and the minimum rightward deviation angle of the drill hole; the minimum downward depression angle of drill hole cC and the minimum leftward deviation angle of the drill hole; the minimum downward depression angle of drill hole dD and the minimum rightward deviation angle of the drill hole. Based on the arrangement of the drill hole angles, calculate the lengths of the 4 drill holes on this basis. The lengths need to ensure that the distal end of the positioning guide wheel passes through the coal seam. In some embodiments, the diameter of the drill hole is set to 160mm.

[0069] The following data are calculated by combining the coal seam occurrence data and the roadway width and height detected by the drilling rig with the maximum or minimum distances required by the outburst prevention requirements, including two cases: the first case is when the coal seam dip and the roadway heading are not on the same line, and the second case is when the coal seam dip and the roadway heading are on the same line, that is, perpendicular to the coal seam (special case). The two cases have different general formulas.

[0070] The first case: The coal uncovering roadway is usually set at 90° considering the cost and the angle between the coal seam strike. Here, let the minimum normal distance between the coal uncovering roadway working face and the coal seam be M, the first control distance be N, the second control distance be W, the coal seam dip angle be α, and the height and width of the roadway be both D; the width of the coal seam be H.

[0071] Calculate that the general formulas for the corresponding drill hole angles and lengths are:

[0072] The minimum upward elevation angle of drill hole aA θ aA is:

[0073] Formula (1);

[0074] The minimum leftward deviation angle of drill hole aA when drilling leftward ε aA is:

[0075] Equation (2);

[0076] The length of borehole aA L aA is:

[0077] Equation (3).

[0078] Similarly:

[0079] The minimum upward elevation angle of borehole bB θ bB is:

[0080] Equation (4);

[0081] The minimum rightward deflection angle of borehole bB ε bB is:

[0082] Equation (5);

[0083] The length of borehole bB L bB is:

[0084] Equation (6).

[0085] Correspondingly, find:

[0086] The minimum downward depression angle of borehole cC θ cC is:

[0087] Equation (7).

[0088] The minimum rightward deflection angle of borehole cC ε cC is:

[0089] Equation (8);

[0090] The length of borehole cC L cC is:

[0091] Equation (9);

[0092] Similarly obtained:

[0093] The minimum downward depression angle of borehole dD θ dD is:

[0094] Equation (10).

[0095] The minimum leftward deflection angle of borehole dDε dD is:

[0096] Equation (11);

[0097] The length of the borehole dD L cC is:

[0098] Equation (12);

[0099] At the same time, it is also necessary to ensure that:

[0100] Equation (13).

[0101] The second case, a special case - when perpendicular to the coal seam:

[0102] The minimum upward elevation angle of the borehole aA θ aA and the minimum upward elevation angle of the borehole bB θ bB and the minimum downward depression angle of the borehole cC θ cC and the minimum downward depression angle of the borehole dD θ dD are the same, and the minimum deviation angle of the borehole aA to the left ε aA and the minimum deviation angle of the borehole bB to the right ε bB and the minimum deviation angle of the borehole cC to the left ε cC and the minimum deviation angle of the borehole dD to the right ε dD are the same, and all are:

[0103] Equation (14);

[0104] The length of the borehole bB L bB and the length of the borehole bB L bB and the length of the borehole cC L cC and the length of the borehole dD L dD are all:

[0105] Equation (15).

[0106] According to the drilling control target area of this implementation technology, it covers the drilling control range in the "Regulations on the Prevention and Control of Coal and Gas Outbursts", enabling the target range of wire saw cutting the coal seam for pressure relief and permeability enhancement to meet the requirements of coal seam gas pressure relief and permeability enhancement. At the same time, the design of this inclined drilling is different from the parallel drilling design of marble mining and the traditional reverse cutting method, and it can completely retain the rock mass in front of the cross-cut coal uncovering working face to act as the role of a safety rock pillar, preventing the release of the elastic energy of the coal body and the expansion energy of the gas.

[0107] In an implementation manner, on the premise that the included angle between the coal uncovering roadway and the coal seam strike is set to 90°, the minimum normal distance from the working face of the coal uncovering roadway to the coal seam is 7m, the first control distance is 12m, the second control distance is 5m, the coal seam dip angle is 80°, and the height and width of the roadway are 4m; the width of the coal seam is 3m. Substituting the above formula to calculate the angles of each drilling hole when the coal seam is not vertical (the first case) are as follows:

[0108] The minimum upward elevation angle of borehole aA θ aA is: 52°;

[0109] The minimum leftward deflection angle of borehole aA ε aA is: 59.4°;

[0110] The length of borehole aA L aA is: 32.5m;

[0111] The minimum upward elevation angle of borehole bB θ bB is: 52°;

[0112] The minimum rightward deflection angle of borehole bB ε bB is: 59.4°;

[0113] The length of borehole bB L bB is: 32.5m;

[0114] The minimum downward depression angle of borehole cC θ cC is: 50°;

[0115] The minimum rightward deflection angle of borehole cC ε cC is: 59.4°;

[0116] The length of borehole cC L cC is: 48.3m;

[0117] The minimum downward depression angle of borehole dD θ dDis: 50°;

[0118] The minimum left deflection angle of the drill hole dD ε dD is: 59.4°;

[0119] The length of the drill hole dD L cC is: 48.3 m.

[0120] The calculated value verified and substituted into Equation (13) is:

[0121] 5.79 m > 5 m.

[0122] In another embodiment, on the premise that the included angle between the coal uncovering roadway and the coal seam strike is set to 90°, the minimum normal distance from the working face of the coal uncovering roadway to the coal seam is 7 m, the first control distance is 12 m, the second control distance is 5 m, the coal seam dip angle is 90°, the height and width of the roadway are 4 m; the width of the coal seam is 3 m. Substituting the above into the formula to calculate the angles of each drill hole in the special case - when perpendicular to the coal seam (the second case) are all:

[0123] ;

[0124] The lengths of each drill hole are all:

[0125] .

[0126] Step S3, use a wire saw machine with a wire saw to cut out a target space connecting the coal seam drill holes based on the drill holes in the coal seam. Among them, the wire saw machine first uses the reverse cutting method to cut out the top surface AabB and two side surfaces (side surface AadD and side surface BbcC) of the target space with the wire saw, and then uses the nested cutting method to cut out the bottom surface DdcC of the target space of the coal seam drill hole. In some embodiments, in the drill hole space, to facilitate the threading operation of the nested cutting method later, the diameter of the wire saw used in the process of the reverse cutting method needs to be greater than the diameter of the wire saw in the process of the nested cutting method.

[0127] In some embodiments, the specific steps of cutting out the top surface AabB of the target space of the coal seam drill hole by the reverse cutting method all include:

[0128] Step S311, adjust the angles of the support frames 7a, 7b and the positioning guide wheels 5a, 5b in the drill holes aA, bB, so that the central planes of the positioning guide wheels 5a, 5b are in the same plane as the cutting surface AabB;

[0129] Step S312, wind the wire saw 8 around the positioning guide wheels 5a, 5b, and use the hydraulic telescopic rods 6a, 6b to push the wire saw 8 and the positioning guide wheels 5a, 5b into the drill holes aA and bB together, and fix them at the pre-cut point;

[0130] Step S313, at this time, lead the wire saw 8 at the outer end to the rotary wheels 4a, rotary wheels 4b, tensioning wheels 3a, tensioning wheels 3b and the wire saw machine 1.

[0131] Step S313, determine the reverse cutting circuit, and the reverse cutting circuit is: wire saw machine 1 → tensioning wheel 3b → rotary wheel 4b → positioning guide wheel 5b → rock mass at point b → rock mass at point a → positioning guide wheel 5a → rotary wheel 4a → tensioning wheel 3a → wire saw machine 1;

[0132] Step S314, before cutting, it is necessary to adjust the positions of the tensioning wheel 3a, tensioning wheel 3b and the wire saw machine 1 to make the wire saw 8 in a pre-tensioned state to prevent the wire from coming off.

[0133] Step S315, turn on the wire saw machine 1, cut the coal seam rock mass at a constant speed, and achieve forward cutting by the backward movement of the wire saw machine 1 and coordinating the tensioning wheel 3a and tensioning wheel 3b to continuously tighten the wire saw 8, so as to achieve the purpose of reverse cutting;

[0134] Step S316, after the wire saw 8 cuts through the coal seam, in order to avoid damage to the slot, the wire saw needs to retract the wire along the original path, keep the wire saw in a tensioned state unchanged, the wire saw machine 1 slowly retreats, and slowly cut the wire saw 8 out of the rock mass to the roadway working face, and reduce the speed to take in the wire, preparing for the next cutting.

[0135] In some embodiments, the specific steps of using the reverse cutting method to cut out the side surface AadD of the target space of the coal seam borehole all include:

[0136] Step S321, adjust the angles of the support frames 7a, support frames 7d and the positioning guide wheels 5a, positioning guide wheels 5d in the boreholes aA and dD to make the central planes of the positioning guide wheels 5a and positioning guide wheels 5d in the same plane as the cutting surface AadD;

[0137] Step S322, wind the wire saw 8 around the positioning guide wheels 5a and 5d, and use the hydraulic telescopic rods 6a and 6d to push the wire saw 8 and the positioning guide wheels 5a and 5d into the boreholes aA and dD together and fix them at the pre-cutting point;

[0138] Step S323, at this time, lead the wire saw at the outer end to the rotary wheels 4a, rotary wheels 4d, tensioning wheels 3a, tensioning wheels 3d and the wire saw machine 1.

[0139] Step S323, determine the reverse cutting circuit, and the reverse cutting circuit is: wire saw machine 1 → tensioning wheel 3a → rotary wheel 4a → positioning guide wheel 5a → rock mass at point a → rock mass at point d → positioning guide wheel 5d → rotary wheel 4d → tensioning wheel 3d → wire saw machine 1;

[0140] Step S324: before cutting, the rope saw is put in a pre-tensioned state by adjusting the positions of the tensioning wheel 3a, the tensioning wheel 3d and the rope saw machine 1 to prevent the rope from coming off.

[0141] Step S325, turning on the wire saw machine 1, cutting the coal seam rock mass at a uniform speed, and continuously tightening the wire saw 8 to achieve forward cutting by moving the wire saw machine 1 backward and coordinating the tensioning wheels 3a and 3d, so as to achieve the purpose of reverse cutting;

[0142] Step S326, after the rope saw 8 cuts through the coal seam, in order to avoid the seam being damaged, the rope saw needs to be retracted along the original path to keep the rope saw in a tensioned state. The rope saw machine 1 slowly retreats, and the rope saw 8 slowly cuts out the rock mass to the working surface of the tunnel, and then slows down and retracts the rope to prepare for the next cutting.

[0143] In some embodiments, the specific steps of cutting out the side surface BbcC of the target space of the coal seam drilling hole by the reverse cutting method include:

[0144] Step S331, adjusting the angles of the support frame 7b, support frame 7c and the positioning guide wheel 5b, positioning guide wheel 5c in the borehole bB, borehole cC, so that the center plane of the positioning guide wheel 5b, positioning guide wheel 5c is in the same plane with the cutting surface BbcC;

[0145] Step S332, winding the rope saw 8 around the positioning guide wheel 5b and the positioning guide wheel 5c, and using the hydraulic telescopic rod 6b and the hydraulic telescopic rod 6c to push the rope saw 8 and the positioning guide wheel 5b and the positioning guide wheel 5c into the borehole bB and the borehole cC, and fix them at the pre-cutting point;

[0146] Step S333, at this time, the outer end of the rope saw is connected to the rotary wheel 4b, the rotary wheel 4c, the tension wheel 3b, the tension wheel 3c and the rope saw machine 1;

[0147] Step S333, determining the reverse cutting loop, which is: rope saw machine 1→tensioning wheel 3b→rotating wheel 4b→positioning guide wheel 5b→rock mass at point b→rock mass at point c→positioning guide wheel 5c→rotating wheel 4c→tensioning wheel 3c→rope saw machine 1;

[0148] Step S334, before cutting, the rope saw needs to be in a pre-tensioned state by adjusting the positions of the tension wheel 3b, the tension wheel 3c and the rope saw machine 1 to prevent the rope from falling off;

[0149] Step S335, turning on the wire saw machine 1, cutting the coal seam rock mass at a uniform speed, and by moving the wire saw machine 1 backward and coordinating the tensioning wheels 3b and 3c to continuously tighten the wire saw 8 to achieve forward cutting, so as to achieve the purpose of reverse cutting;

[0150] Step S336, after the wire saw 8 cuts through the coal seam, to prevent damage to the slot, the wire saw needs to retract along the original path to keep the wire saw in a taut state. The wire saw machine 1 slowly retreats, and the wire saw slowly cuts into the rock mass to the roadway working face, then reduces the speed and retracts the wire saw to prepare for the next cut.

[0151] During the reverse cutting process, it is necessary to pay attention to installing a water inlet device at the rope inlet end. When performing side cutting, it is necessary to adjust the upper drill hole as the rope inlet end to utilize the self - gravity of water, improve the water - carrying capacity of the wire saw, discharge the coal and rock debris cut by the wire saw, and moisten the coal seam rock mass at the same time.

[0152] Install a local ventilator at the roadway to strengthen ventilation, and install a remote gas monitoring system at the working face to monitor the gas concentration at the working face in real - time. If the gas concentration is too high, the rotation speed of the wire saw machine can be remotely controlled at any time to reduce the cutting speed to control the gas concentration and prevent gas over - limit.

[0153] In some embodiments, based on the reverse - cut top surface AabB, side surface AadD, and side surface BbcC slot spaces described above, the specific steps of using the nested - cutting method to cut out the target space ABCD for coal seam pressure relief and permeability enhancement all include:

[0154] Step S341, wind the wire saw 8 around the positioning guide wheels 5a, 5b, 5c, and 5d at the same time. Adjust the center planes of the positioning guide wheels 5a and 5d in the drill holes aA and dD to be parallel to the side surface AadD, and the center planes of the positioning guide wheels 5b and 5c in the drill holes bB and cC to be parallel to the side surface BbcC, and keep the wire saw taut. At this time, adjusting the center planes of the positioning guide wheels 5a and 5b in the drill holes aA and bB to be parallel to the side surface AadD and the side surface BbcC respectively not only plays a positioning role for the wire saw cutting, but also cooperates with the removal of the inner support frame tripod legs. When retracting the hydraulic telescopic rods 6a and 6b, it can avoid the tripod legs of the support frames 7a and 7b crossing and hanging on the wire saw 8, affecting the cutting position; at the same time, it also avoids the tripod legs of the support frames 7c and 7d hanging on the wire saw 8 when the wire saw cuts out after the nested - cutting is completed.

[0155] Step S342, use the hydraulic telescopic rods 6a, 6b, 6c, and 6d and move the wire saw machine 1 to slowly push the four positioning guide wheels 5a, 5b, 5c, and 5d to the pre - cut surface ABCD, so that the distal ends of the four positioning guide wheels 5a, 5b, 5c, and 5d are in the same plane as the pre - cut surface ABCD. Then retract the hydraulic telescopic rods 6a and 6b in the drill holes aA and bB to withdraw the upper two positioning guide wheels 5a and 5b. At this time, the rope - sleeving operation is completed;

[0156] Step S343: Connect the external wire saw 8 to the rotary wheels 4d, 4c, tensioning wheels 3d, and 3c at the bottom surface DdcC and connect to the wire saw machine 1.

[0157] Step S344: Determine the circumferential cutting loop. The circumferential cutting loop is: wire saw machine 1 → tensioning wheel 3d → rotary wheel 4d → positioning and guiding wheel 5d → coal and rock mass at point A → coal and rock mass at point B → positioning and guiding wheel 5c → rotary wheel 4c → tensioning wheel 3c → wire saw machine 1.

[0158] Step S345: Before circumferential cutting, adjust the positions of the tensioning wheels 3d, 3c, and the wire saw machine 1 to also keep the wire saw 8 in a pre-tensioned state to prevent the wire from slipping off.

[0159] Step S346: Turn on the wire saw machine 1 and cut the coal and rock mass at a constant speed. Through the backward movement of the wire saw machine 1 and the coordination of the tensioning wheels 3d and 3c, the wire saw 8 is continuously tightened to achieve upward and downward cutting.

[0160] Step S347: When the wire saw cuts to the connection line at the lower ends of the two positioning and guiding wheels 5d and 5c in the drill holes cC and dD, the positioning and guiding wheels in the drill holes lose their function, and the two rotary wheels 4d and 4c at the exits of the drill holes cC and dD act as positioning and guiding wheels.

[0161] Step S348: At this time, the wire saw 8 retracts the wire and still maintains the cutting state. The wire saw is in a tensioned state. Slowly move the wire saw machine 1 backward to prevent the wire from slipping off.

[0162] Step S349: The wire saw winds around and cuts from the bottom surface DdcC position to the working face of the crossheading roadway, and decelerates to take in the wire. Prepare for the next circumferential cutting.

[0163] During the circumferential cutting process, it is necessary to pay attention to installing a water inlet device in the drill hole at the upper end of the wire inlet, and also install a local ventilator in the roadway to monitor the gas concentration of the working face, so as to adjust the cutting speed of the wire saw at any time, control the gas concentration, and prevent gas overrun.

[0164] After the coal and rock mass is cut off, due to the gravity settlement of the coal and rock mass, the slot cut out at the bottom surface and the slot cut out during wire retraction are compressed or even closed. Subsequent circumferential cutting operations need to be carried out using the two side surfaces AadD, BbcC, and the top surface AabB for wire threading work.

[0165] Repeat the above nested cutting steps. By shortening the advancing distances of the four positioning guide wheels 5a, positioning guide wheel 5b, positioning guide wheel 5c, and positioning guide wheel 5d, control the pre-cut surface ABCD cut inside the coal seam, perform multiple cuts on the coal seam from far to near, and conduct an effect inspection on the coal seam after multiple cuts. According to the "Regulations on the Prevention and Control of Coal and Gas Outbursts", when the maximum expansion deformation of the pressure-relieved coal seam in a outburst-prone mine is greater than 0.3%, the requirement for pressure relief and permeability enhancement is met.

[0166] Therefore, the subsidence amount of the upper boundary of the coal seam can be monitored Q 1 and the expansion amount of the lower boundary Q 2 , to calculate the maximum expansion deformation rate ζ of the coal body. The judgment formula is:

[0167] Equation (16);

[0168] H represents the original thickness of the coal seam; h represents the width of the slot (the diameter of the wire saw); n represents the number of slotting times.

[0169] At this time, it can be considered that multiple wire saw slotting provides sufficient space for the deformation of the coal body and the pressure relief is sufficient.

[0170] By continuously creating slots in the coal seam through diamond bead wire saw cutting, space is provided for the release of coal seam stress, the channels for gas release are increased, and at the same time, the exposed area of the coal body is increased, ultimately effectively releasing gas pressure and in-situ stress; the cutting process has less damage to the coal and rock mass, and the cut coal and rock mass has the characteristics of an irregular hexahedron. The cutting coal surface is much larger than the working face of the driving roadway. This "large inside and small outside" geometric feature provides a natural barrier to prevent the energy of gas outburst.

[0171] The present invention performs positioning cutting on the coal seam rock mass by adjusting the drilling angle and the length of the telescopic rod. The wire saw slotting pressure relief and permeability enhancement technology can continuously slot in the coal seam with a large cutting range, and often can achieve the purpose of stress release through several cuts, realizing large-area permeability enhancement of the coal seam.

[0172] Meanwhile, the wire saw cutting process has a strong water-carrying capacity. This water can moisten the coal and rock mass, weaken the brittleness of the coal and rock mass, increase its plasticity, and reduce its elastic energy. In addition, the water brought into the coal body during the nested cutting process can reduce the desorption rate of the residual gas in the coal body and the gas expansion energy after the coal body is moistened. According to the requirements of outburst prevention during cross-measurement gateway uncovering coal seams, the control range of the cross-cutting boreholes is often larger than the outline of the roadway at the coal uncovering location. Therefore, the coal and rock mass cut by the present invention presents a "larger inside and smaller outside" shape feature and still retains the protective effect of the safety rock pillar, providing a barrier to prevent the outburst energy of gas. By cutting the coal seam multiple times and with multiple slots and discharging the cut coal chips by adjusting the cutting direction of the wire saw and its water-carrying capacity, conditions are provided for the expansion and deformation of the coal seam. According to the requirements of the "Regulations on the Prevention and Control of Coal and Gas Outburst" and combined with the measurement of the actual project, the effect of pressure relief and permeability enhancement is determined to determine the number of slotting times. The present invention can be remotely controlled during cutting, realizing unmanned operation at the working face, with fast construction speed, low cost, safety and high efficiency, solving the technical problems in the prior art that although the outburst elimination effect is achieved for the coal seam, the time-consuming for gas drainage through the drainage boreholes is long, and the costs of measures such as hydraulic slotting, punching, and installing metal frameworks are high.

[0173] The foregoing description of specific exemplary embodiments of the invention has been presented for purposes of illustration and example. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that, according to the above teachings, many modifications and variations are possible. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the invention and its practical applications so that those skilled in the art can implement and utilize the various different exemplary embodiments of the invention, as well as various different selections and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for relieving coal seam pressure and eliminating outbursts, characterized in that: The following steps are involved: Use a drilling rig to configure four boreholes on the coal seam, and ensure that the control range of the four boreholes is greater than the first control distance outside the coal mining tunnel contour line, and the minimum distance from the outer edge of the control range of the four boreholes to the coal mining tunnel contour line is not less than the second control distance; the angle of the boreholes in the coal seam is determined based on the coal seam occurrence, and the coal seam occurrence includes the direction, dip, inclination and thickness of the coal seam, and the coal seam occurrence is explored by conducting geological drilling in the coal seam in the extraction tunnel; Using a wire saw machine (1) with a wire saw (8) to cut out a target space connected to the borehole in the coal seam based on the borehole in the coal seam, wherein the wire saw machine (1) first uses a reverse cutting method to cut out the top surface and two side surfaces of the target space through the wire saw (8) and then uses a sleeve cutting method to cut out the pressure relief and permeability enhancement target space; The coal seam occurrence includes two situations: the first situation is when the coal seam dip is not on the same line as the roadway strike; the second situation is when the coal seam dip is on the same line as the roadway strike, which is a vertical coal seam. The two situations have different general formulas: The first case: the angle between the coal mining tunnel and the coal seam is set to 90°. Here, the minimum normal distance between the working face of the coal mining tunnel and the coal seam is set to M, the first control distance is N, the second control distance is W, the coal seam inclination is α, the height and width of the tunnel are both D; the thickness of the coal seam is H; The corresponding drilling angle and length are calculated as follows: Minimum upward elevation angle of borehole aA θ aA for: Formula (1); Minimum deviation angle of drilling hole aA to the left ε aA for: Formula (2); Length of drilling hole aA L aA for: Formula (3); The second case, when the coal seam is vertical: Minimum upward elevation angle of borehole aA θ aA , Minimum upward elevation angle of borehole bB θ bB 、Minimum downward depression angle of borehole cC θ cC 、Minimum downward depression angle of drilling hole dD θ dD Same as the minimum left deviation angle of borehole aA ε aA , Minimum deviation angle of drilling hole bB to the right ε bB 、Minimum deviation angle of drilling hole cC to the left ε cC , the minimum deviation angle of drilling hole dD to the right ε dD The same are: ； Length of drilling hole aA L aA , length of drilling hole bB L bB , length of drilling hole cC L cC , the length of the drilling hole dD L dD Both are: 。 2. The method for relieving coal seam pressure and eliminating outburst according to claim 1, characterized in that: The specific steps of cutting out the top surface and two side surfaces of the target space by the reverse cutting method include: First, adjusting the angles of the corresponding two sets of wire saw positioning guides so that the central planes of the two sets of wire saw positioning guides are parallel to the plane of the target space; Then, the rope saw (8) is passed around the two sets of rope saw positioning guide parts, and the rope saw (8) and the two sets of rope saw positioning guide parts are pushed into the corresponding boreholes together using the corresponding position adjustment parts, and fixed at the pre-cutting point, and the rope saw (8) is connected to the two sets of rope saw movement direction adjustment parts, the two sets of rope saw tensioning parts and the rope saw machine (1); Then determine the reverse switching circuit; Finally, the wire saw machine (1) is started to cut the coal seam at a uniform speed. At the same time, through the backward movement of the wire saw machine (1) and the coordination of the wire saw tensioning unit, the wire saw (8) is kept tensioned and continuous forward cutting is achieved, thereby completing the reverse cutting process.

3. The method for relieving coal seam pressure and eliminating outbursts according to claim 2, characterized in that: The reverse cutting loop comprises, in order: a rope saw machine (1), a set of rope saw tensioning parts, a set of rope saw movement direction adjusting parts, a set of rope saw positioning guide parts, a rock mass at one point, another rock mass at another point, another set of rope saw positioning guide parts, another set of rope saw movement direction adjusting parts, another set of rope saw tensioning parts, and a rope saw machine (1).

4. The method for relieving coal seam pressure and eliminating outburst according to claim 3, characterized in that: Before cutting, the rope saw (8) needs to be in a pre-tensioned state by adjusting the position of the rope saw tensioning part and the rope saw machine (1).

5. The method for relieving coal seam pressure and eliminating outbursts according to claim 3, characterized in that: After the rope saw (8) has cut through the coal seam, the rope saw (8) is retracted along the original path, the rope saw (8) is kept in a tensioned state, the rope saw machine (1) is retracted, and the rope saw (8) is cut out of the rock mass to the working surface of the tunnel, and then the speed is reduced and the rope is retracted to prepare for the next cutting.

6. The method for relieving coal seam pressure and eliminating outbursts according to claim 2, characterized in that: The rope saw movement direction adjustment part is a rotary wheel, the rope saw tensioning part is a tensioning wheel, the rope saw positioning guide part is a positioning guide wheel, and the position adjustment part is a hydraulic telescopic rod; The method of cutting out the target space for pressure relief and anti-reflection by using the sleeve cutting method comprises: Step S341, winding the rope saw (8) around the positioning guide wheel 5a, the positioning guide wheel 5b, the positioning guide wheel 5c, and the positioning guide wheel 5d at the same time, adjusting the center planes of the positioning guide wheels 5a and 5d in the boreholes aA and dD to be parallel to the side surface AadD, and the center planes of the positioning guide wheels 5b and 5c in the boreholes bB and cC to be parallel to the side surface BbcC, and keeping the rope saw taut; Step S342, using the hydraulic telescopic rod 6a, the hydraulic telescopic rod 6b, the hydraulic telescopic rod 6c, and the hydraulic telescopic rod 6d and moving the rope saw machine (1) to slowly push the four positioning guide wheels 5a, the positioning guide wheels 5b, the positioning guide wheels 5c, and the positioning guide wheels 5d to the pre-cutting surface (ABCD), so that the distal ends of the four positioning guide wheels 5a, the positioning guide wheels 5b, the positioning guide wheels 5c, and the positioning guide wheels 5d are in the same plane as the pre-cutting surface (ABCD), and then the hydraulic telescopic rod 6a and the hydraulic telescopic rod 6b in the borehole aA and the borehole bB are retracted to withdraw the upper two positioning guide wheels 5a and the positioning guide wheels 5b, and the rope wrapping operation is now completed; Step S343, the outer end of the rope saw (8) is connected to the rotating wheel 4d, the rotating wheel 4c, the tensioning wheel 3d, and the tensioning wheel 3c at the bottom surface (DdcC) and connected to the rope saw machine (1); Step S344, determining the cutting loop, which is in the following order: rope saw machine (1), tension wheel 3d, rotary wheel 4d, positioning guide wheel 5d, coal rock mass at point A, coal rock mass at point B, positioning guide wheel 5c, rotary wheel 4c, tension wheel 3c, rope saw machine (1); Step S345, before cutting, the rope saw (8) needs to be in a pre-tensioned state by adjusting the tension wheel 3d, the tension wheel 3c and the position of the rope saw machine (1) to prevent the rope from coming off; Step S346, turning on the wire saw machine (1) to cut the coal and rock mass at a uniform speed, and by moving the wire saw machine (1) backward and coordinating the tensioning wheels 3d and 3c to continuously tighten the wire saw (8) to achieve upward and downward cutting; Step S347, when the rope saw cuts to the line connecting the lower ends of the two positioning guide wheels 5c and 5d in the borehole cC and the borehole dD, the positioning guide wheels in the borehole lose their function, and the two rotary wheels 4c and 4d at the exit of the borehole cC and the borehole dD serve as the positioning guide wheels; Step S348, at this time, the rope saw (8) is retracted while still maintaining the cutting state, and the rope saw (8) is in a tensioned state, so that the rope saw machine (1) moves backward to prevent the rope from falling off; Step S349, the rope saw (8) cuts from the bottom surface (DdcC) to the working surface of the stone gate tunnel, and decelerates and retracts the rope.

7. The method for relieving coal seam pressure and eliminating outbursts according to claim 6, characterized in that: The method of cutting out the target space for pressure relief and anti-reflection by using the sleeve cutting method also includes: Repeat the steps S341 to S349, and control the position of the slot cut inside the coal seam by shortening the advancing distance of the four sets of rope saw positioning guide parts, cut the coal seam multiple times from far to near, and inspect the effect of the coal seam after multiple cuttings, and highlight that the maximum expansion deformation of the unloaded coal seam in the mine is greater than 0.3%, which meets the requirements of unloading and permeability enhancement; By monitoring the subsidence Q1 of the upper boundary of the coal seam and the expansion Q2 of the lower boundary, the maximum expansion deformation rate ζ of the coal body is calculated. The determination formula is: H represents the original thickness of the coal seam; h represents the width of the slot; and n represents the number of cuts.

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