Layout method of mine gas extraction drilling field and drilling hole

Abstract

The application relates to the field of gas prevention and control in coal mining, and particularly discloses a layout method of a mine gas extraction drilling field and a drilling hole, which comprises the following steps: step 1: after determining a first-mining protective layer, a roadway is excavated along a horizontal direction to the protective layer, and a through-hole drilling is used to pre-extract a gas area of a coal uncovering face to prevent outburst during the excavation process; step 2: a parallel return airway and a transportation roadway are excavated along the strike of the first-mining protective layer, and a drilling hole is used to prevent outburst by combining with a side-excavation and extraction and a pre-discharge drilling hole during the excavation process; and step 3: a bedding drilling hole is used to pre-extract coal bodies between the return airway and the transportation roadway; wherein the drilling hole of the drilling field in steps 1 and 2 adopts a high-rotation-speed spiral drilling process and a dry drilling process, so as to facilitate slow discharge of gas during the drilling process and avoid gas gathering and jetting.

Description

Technical Field

[0001] This invention relates to the field of coal mining gas control, specifically to the layout method of mine gas extraction drilling sites and boreholes. Background Technology

[0002] my country is a major energy consumer, with coal seams accounting for over 60% of its primary energy consumption, and this proportion will remain significant for a considerable period. Coal mining in my country is primarily conducted underground. Due to the extremely complex geological conditions of coal seams, geological disasters are frequent during mining operations, leading to extremely negative social impacts. Gas is considered the number one killer in coal mines, making gas disaster prevention a key aspect of safety work. Currently, gas drainage mainly relies on boreholes to extract gas from coal seams. For outburst-prone mines, the number of drainage boreholes required for gas control is even greater; in some outburst-prone mines, the drilling work for draining 10,000 tons of gas reaches over 1,000 meters.

[0003] Among the typical disasters caused by gas outbursts, the most dangerous are those occurring during coal seam exposure and roadway excavation in stone gates, where the amount of coal outburst is generally over several hundred tons, and the outburst gas exceeds tens of thousands of cubic meters. Compared to coal mining faces, the space in stone gate coal seams is limited, leading to more concentrated gas emissions. This is accompanied by problems such as coal seam fracturing and high gas pressure. Furthermore, high-gas coal seams generally possess natural properties of low permeability, strong adsorption, and slow desorption rates. During drilling, complex situations such as blowouts, borehole collapses, and stuck drill bits are prone to occur. Current drilling techniques primarily employ water-cooled drilling, using water as a flushing medium to carry away and remove drill cuttings and to cool the drill bit. However, due to the high density of water and the high pump pressure during drilling, the scouring force during drilling is strong, which can easily lead to the collapse and instability of the borehole wall. At the same time, water can easily enter the coal body along the coal seam fissures, and the overall mechanical strength of the coal body is reduced under the action of water tension. In addition, the water in the borehole will hinder the release and outflow of gas. When the gas pressure accumulates, it can easily form a blowout, which brings serious safety hazards. Summary of the Invention

[0004] The purpose of this invention is to provide a method for the layout of mine gas drainage drilling sites and boreholes, so as to promote the continuous release of gas during the drilling process of coal seam exposure and roadway excavation, and avoid the phenomenon of blowout caused by gas pressure accumulation.

[0005] The layout method for mine gas drainage drilling sites and boreholes includes the following steps:

[0006] Step 1: After determining the first mining protective layer, the development roadway is excavated horizontally to the protective layer. During the excavation process, cross-layer drilling is used to pre-drain the gas area of ​​the coal face at the rock gate to prevent outbursts.

[0007] The steps for preventing gas outbursts in the gas-prone area of ​​a cross-layer drilling pre-drainage rock-gate coal uncovering face are as follows:

[0008] Step 1-1: Determine the outline of the roadway at the coal seam exposure point in the tunneling direction based on the coal seam dip angle;

[0009] Steps 1-2: Drilling should be carried out 7m before the minimum normal distance between the coal face and the coal seam, and the starting position of the drilling site should be at the center of the shaft.

[0010] Steps 1-3: The control range of the drilling site is at least 12m outside the roadway outline at the coal seam exposure point, the final hole spacing is 3-4.0m, and the drilling length is 0.5-0.8m from the coal seam to the roof.

[0011] Steps 1-4: Drilling is completed using high-speed spiral drilling technology. The high-speed spiral drilling speed is greater than or equal to 400 r / min and less than or equal to 800 r / min. Dry drilling is used in the drilling process.

[0012] Step 2: Excavate the return airway and transport roadway parallel to the strike of the first mining protective coal seam. During the excavation process, adopt the measures of simultaneous excavation and drainage combined with advance drainage borehole anti-outburst measures.

[0013] The steps for preventing borehole outbursts by combining excavation and extraction with advanced drainage are as follows:

[0014] Step 2-1: Conduct advance drilling directly in front of the tunneling face;

[0015] Step 2-2: Drilling sites are set up on both sides of the roadway behind the tunneling face. The drilling sites are inclined along the tunneling direction to pre-drain the coal body within the tunneling influence range. Each group of drilling sites should be arranged alternately on both sides of the coal roadway.

[0016] The discharge borehole in step 2-1 and the pre-extraction borehole in step 2-2 adopt high-speed spiral drilling technology. The high-speed spiral drilling speed is greater than or equal to 400 r / min and less than or equal to 800 r / min. The drilling process adopts dry drilling.

[0017] Step 3: Pre-extraction of the coal seam between the return airway and the transport roadway using in-seam drilling.

[0018] The beneficial effects of this basic scheme are as follows:

[0019] During coal mining, the risk of gas outbursts is greatest during roadway excavation, particularly at the coal seam exposure face. To mitigate this risk, boreholes are pre-drilled to extract and release gas from the coal seam ahead during excavation. Therefore, in the coal seam exposure face, a cross-layer drilling technique is employed to fully release gas from the coal seam. During the excavation of return airways and transport roadways, advance drainage boreholes are laid out on the working face, while pre-extraction boreholes are laid out diagonally on both sides of the roadway to avoid the risk of sudden gas release during the excavation of return airways and transport roadways. During coal mining, in-seam pre-extraction drilling sites are laid out on the coal seam.

[0020] In the drilling process of the coal seam uncovering face and the drilling process of the return airway and transport roadway, high-speed spiral drilling technology is used to complete the drilling. The speed of high-speed spiral drilling is greater than or equal to 400 r / min and less than or equal to 800 r / min. This technology increases the speed of the drill bit and does not pressurize water into the hole during the drilling process, which is conducive to the slow discharge of gas during the drilling process and avoids gas accumulation and blowout phenomenon.

[0021] Preferred Option 1: As a further optimization of the basic option, in steps 1-3, the extraction radius is 2m, the final hole spacing is 4.0m, and the borehole diameter is 75mm.

[0022] Preferred Option 2: As a further optimization of Preferred Option 1, in step 2, the drilling sites are located 5m behind the working face on both sides of the roadway. Within each drilling site, 12 extraction boreholes are arranged along the tunneling direction, with 6 boreholes in each of the left and right drilling sites. The distance from the starting position to the ending position of each borehole in the tunneling direction is 60m, and the distances from the ending position to the center line of the tunneling are 2m, 6m, 10m, 14m, 18m, and 20m, respectively. By arranging drilling sites on both sides of the roadway, the concentrated outburst of gas within the tunneling influence area is controlled, thereby intercepting the gas.

[0023] Preferred Option 3: As a further optimization of Preferred Option 2, in steps 1-4, the high-speed spiral drilling rotation speed is 600 r / min. The risk of gas outburst is greater in the rock-gate coal seam, and the rock-gate is relatively harder than the coal seam; therefore, a higher rotation speed is used for drilling, improving drilling efficiency.

[0024] Preferred Option 4: As a further optimization of Preferred Option 3, in step 2, the high-speed auger drilling rotation speed is 400 r / min. The borehole in step 2 is a joint borehole, and since the hardness of the coal seam is lower than that of the rock, a lower rotation speed is used to avoid borehole collapse while still meeting the high-speed drilling speed requirement.

[0025] Preferred Option 5: As a further optimization of Preferred Option 4, in steps 1 and 2, the high-speed spiral drilling process uses a high-speed spiral slag removal drilling machine for drilling; the high-speed spiral slag removal drilling machine includes a traveling device, a double-headed motor fixed on the traveling device, a rotating rod connected to the double-headed motor, and a drill bit connected to the end of the rotating rod.

[0026] The rotating rod includes an inner rod and an outer rod. The outer rod is sleeved outside the inner rod and coaxially arranged. The inner rod and the outer rod are connected by a slip ring, forming an exhaust channel between them. The slip ring has a through hole on its circumference, allowing the exhaust channel to be connected front and back. The drill bit is fixed to the end of the outer rod of the rotating rod. The drill bit has a receiving interface at its center, allowing the end of the inner rod to be inserted into the receiving interface. The receiving interface extends through to the cutting end of the drill bit and connects to the outside. An air inlet is provided on the central axis of the inner rod, through which air can be supplied to the drill bit during drilling.

[0027] The outer surface of the rotating rod is provided with a spiral groove, and the outer rod is provided with an air hole that penetrates the side wall of the outer rod. The air hole is connected to the exhaust channel, and a filter screen is welded to the end of the air hole near the exhaust channel. An axial flow fan blade is welded to the inner rod of the rotating rod. When the inner rod rotates, it will form an axial airflow in the exhaust channel inside the rotating rod.

[0028] The dual-head motor can drive the inner and outer rods of the rotating rod to rotate in opposite directions.

[0029] In the preferred embodiment five, the drill bit is driven to rotate by the outer rod of the rotating rod, and an air inlet is provided in the inner rod for supplying air to the drill bit. During the drilling process, airflow is blown into the air inlet, and the airflow blown out from the end of the drill bit has a cooling effect on the drill bit. The airflow will enter the borehole from the bottom, which is conducive to the discharge of gas and debris.

[0030] Secondly, an exhaust channel is formed between the inner rod and the outer rod. The inner rod rotates in the opposite direction, and the axial fan blades on the inner rod create air pressure that causes airflow to be discharged outward in the exhaust channel. Furthermore, several air holes are provided on the side wall of the outer rod. Under the action of air pressure, the gas will be drawn into the exhaust channel, so that the gas can be discharged from the end of the rotating rod in a concentrated manner, avoiding the direct discharge of gas into the working area and causing a gas outburst.

[0031] Preferred Option Six: As a further optimization of Preferred Option Five, the dual-head motor includes a housing, end caps fixed to both ends of the housing by bolts, a stator fixed to the inner wall of the housing, and an outer output shaft rotatably connected to the end caps, with a rotor fixed on the outer output shaft; the outer output shaft is a hollow cylindrical shape, and an inner output shaft is provided inside the outer output shaft, which is coaxial with the outer output shaft and supported by a slip ring; one end of the inner output shaft and the outer output shaft are transmission ends, and the other end is an output end, with the transmission ends being driven by a planetary gear system, and the transmission end of the inner output shaft extending from the left end cap;

[0032] An exhaust channel is formed between the inner drive shaft and the outer drive shaft, and a through hole parallel to the axial direction is provided on the slip ring. An exhaust port is provided on the left end cover corresponding to the exhaust channel. The output end extends from the right end cover, and an air intake is provided on the central axis of the inner output shaft. The output end of the outer output shaft is connected to the outer rod, and the output end of the inner output shaft is connected to the inner rod.

[0033] In preferred embodiment six, the outer and inner output shafts are driven at their ends by a planetary gear train, allowing them to rotate in opposite directions. Furthermore, the inner output shaft rotates at a higher speed than the outer output shaft within this planetary gear train, which helps create external exhaust pressure within the exhaust channel to draw in methane gas. Secondly, an exhaust port is provided on the left end cover corresponding to the exhaust channel to facilitate the concentrated discharge of methane gas.

[0034] Preferred Option 7: As a further optimization of Preferred Option 6, the air hole is a strip-shaped hole, and an exhaust module is installed inside the strip-shaped hole; the exhaust module includes a winding block and a vibrating block slidably connected inside the winding block; the outer periphery of the winding block is provided with a winding groove, and a coil is wound in the winding groove; a conical hole is provided at the center of the winding block; the vibrating block is provided with a conical end that mates with the conical hole; both ends of the vibrating block are slidably connected to the winding block; and the vibrating block is provided with a hole; the reciprocating vibration of the vibrating block can cause the conical end to mate with and separate from the conical hole.

[0035] The filter screen is set on the side of the winding block facing the inner rod, and compression springs are provided on the sides of the vibrating block facing the outer side of the outer rod at both ends, so that the vibrating block forms an oscillator state. The compression springs are made of shape memory alloy. A permanent magnet is fixed on the inner rod at the position corresponding to the location of the winding block.

[0036] In preferred embodiment seven, the outer rod rotates, causing the coil to cut magnetic field lines, thereby inducing a current within the coil and raising its temperature. This causes the compression spring to extend, increasing its stiffness. Specifically, during drilling, when the outer rod rotates at low speeds, the coil generates little heat, and the compression spring is in a short, contracted state, preventing blockage of the conical hole. As the rotational speed increases, the coil temperature rises, the compression spring extends, and a gap forms between the conical end of the vibrating block and the conical hole. At this point, the amplitude and frequency of the vibration driven by the coil increase. Furthermore, the increased rotational speed results in a greater outward centrifugal force on the debris. Therefore, the combination of the vibrating block's vibration and the centrifugal force helps prevent blockage of the conical hole. Attached Figure Description

[0037] Figure 1 A schematic diagram of the mineable coal seams in the mining area;

[0038] Figure 2 The drilling layout along the tunneling direction for pre-extraction rock gate coal uncovering working face with cross-layer drilling;

[0039] Figure 3 Drilling site layout for pre-extraction rock gate coal uncovering working face of cross-layer drilling;

[0040] Figure 4 The layout of the drilling site during the excavation of the return airway and transport roadway;

[0041] Figure 5 Drilling site layout for pre-extraction of coal seam along the seam through boreholes between the return airway and the transport roadway;

[0042] Figure 6 This is a schematic diagram of the structure of a high-speed spiral slag discharge drilling machine;

[0043] Figure 7 This is a schematic diagram of the rotating rod in Embodiment 1;

[0044] Figure 8 This is a schematic diagram of the rotating rod in Embodiment 2;

[0045] Figure 9 for Figure 8 Enlarged view of part A in the middle. Detailed Implementation

[0046] The following detailed description illustrates the specific implementation method:

[0047] The reference numerals in the accompanying drawings include: housing 11, left end cover 12, right end cover 13, stator 14, rotor 15, external output shaft 21, internal output shaft 22, planetary gear train structure 23, rotating rod 30, outer rod 31, inner rod 32, slip ring 33, air intake duct 34, exhaust passage 35, air hole 36, filter screen 37, axial flow fan blade 38, exhaust module 40, permanent magnet 41, winding block 42, coil 43, vibrating block 44, and hole 45.

[0048] As attached Figure 1 As shown, the mineable coal seams in the mining area are mostly 13 seams (Nos. 1, 3, 4, 5-2, 5-3, 7, 10, 13-1, 13-2, 14, 15-2, 16, and 23-2). The average thicknesses of coal seams 1, 3, 4, 5-2, 5-3, 7, 10, 13-1, 13-2, 14, 15-2, 16, and 23-2 are 0.76m, 1.13m, 0.84m, 0.91m, 1.22m, 2.46m, 0.82m, 1.97m, 2.51m, 1.86m, 1.73m, 0.67m, and 0.83m, respectively. The average spacing between coal seams are: 10.20 m, 4.51 m, 10.94 m, 10.77 m, 17.59 m, 6.95 m, 23.08 m, 11.58 m, 26.29 m, 7.85 m, 18.26 m, and 74.69 m.

[0049] Table 1: Overview of Characteristics of Minable Coal Seams

[0050]

[0051] Based on the coal seam spacing, except for the 10 coal seam and the 13-1 coal seam with an average spacing of 29.28m, the 13-2 and 14 coal seams with an average spacing of 26.29m, and the 16 and 23-2 coal seams with an average spacing of 74.69m, which have relatively large spacing, the remaining coal seams have relatively small spacing.

[0052] Based on the spacing between coal seams, the coal seams suitable for initial mining are No. 1, No. 13-1, No. 14, and No. 23-2. Initial mining of No. 13-1, No. 14, and No. 23-2 will not damage the coal seams above them.

[0053] Since 23-2 is the lowest coal seam, buried relatively deep, and is far from the overlying coal seam, the initial mining of 23-2 will have limited protective effect on the overlying coal seam. Therefore, it is not advisable to mine 23-2 as the first coal seam.

[0054] The No. 1 coal seam was initially mined as a protective layer. However, due to its extremely thin thickness (0.65–0.80 m), the actual mining results showed that after pre-draining the No. 1 coal seam along the seam, the thinness of the seam caused the drill bit to drift, making it impossible to guarantee the effective drainage of the No. 1 coal seam itself. This resulted in frequent unresolved outbursts at the No. 1 coal seam face. During the mining of the No. 1 coal seam, production was frequently suspended for re-drilling and pre-draining to resolve the outbursts, leading to long-term disruption of normal production at the face. The No. 1 coal seam could not be continuously mined, and the adjacent protected layers could not be effectively protected and prevented from being drained.

[0055] Table 2: Results of Additional Gas Tests for Each Minable Coal Seam

[0056]

[0057] Table 3: Results of Gas Pressure Tests in Each Minable Coal Seam

[0058]

[0059] According to the data in Table 3 above, the gas pressure in each coal seam is above 2 MPa, and each coal seam has the risk of outburst.

[0060] According to the data in Table 2 above, in terms of coal seam firmness coefficient, seam 1 has a coefficient of 0.42, seam 13-1 has a coefficient of 0.59, and seam 14 has a coefficient of 0.48, with seam 13-1 having the highest coefficient. In terms of initial velocity of gas release, seam 1 has a coefficient of 15, seam 13-1 has a coefficient of 10, seam 14 has a coefficient of 18, with seam 13-1 having the lowest coefficient. In terms of coal seam gas outburst tendency coefficient, seam 1 has a coefficient of 35.7, seam 13-1 has a coefficient of 16.9, and seam 14 has a coefficient of 37.5, with seam 13-1 having the lowest coefficient. Therefore, based on the above gas-related test results, seam 13-1 is suitable for mining as a protective layer.

[0061] Therefore, the design prioritizes mining 13-1 coal seam as a protective layer, which will protect all coal seams above and below it. The remaining coal seams will be mined in the following order from top to bottom: 13-1 coal seam → 1 coal seam → 3 coal seam → 4 coal seam → 5-2 coal seam → 5-3 coal seam → 7 coal seam → 10 coal seam → 13-2 coal seam → 14 coal seam → 15-2 coal seam → 16 coal seam → 23-2 coal seam.

[0062] Example 1:

[0063] The layout of the gas drainage drilling site during the mining process is as follows:

[0064] Step 1: After determining the first mining protective layer, the development roadway is excavated horizontally to the protective layer (i.e., the 13-1 coal seam). During the excavation process, cross-layer drilling is used to pre-drain the gas area of ​​the rock gate coal uncovering face to prevent outbursts.

[0065] like Figure 2 , Figure 3 As shown, the steps for preventing gas outbursts in the gas-prone area of ​​the coal face through-layer drilling pre-drainage are as follows:

[0066] Step 1-1: Determine the outline of the roadway at the coal seam exposure point in the tunneling direction based on the coal seam dip angle;

[0067] Steps 1-2: Drilling should be carried out 7m before the minimum normal distance between the coal face and the coal seam, and the starting position of the drilling site should be at the center of the shaft.

[0068] Steps 1-3: The control range of the drilling site is at least 12m outside the roadway outline at the coal seam exposure point, with a extraction radius of 2m, a final hole spacing of 4.0m, a borehole diameter of 75mm, and a borehole length of 0.5m penetrating the coal seam to the roof. The technical parameters of the borehole from top to bottom are shown in Table 1.

[0069] Steps 1-4: Drilling is completed using high-speed spiral drilling technology. The high-speed spiral drilling speed is greater than or equal to 400 r / min and less than or equal to 800 r / min (in this embodiment, the speed of this step is 600 r / min). Dry drilling is adopted in the drilling process. During the drilling process, air is circulated to the drill bit to drive the drill cuttings out and cool the drill bit.

[0070] The borehole layout diagram for the gas outburst prevention drilling site in the gas-prone area of ​​the coal face under cross-layer pre-drainage rock-excavation gate is obtained by controlling the above parameters; the cross-sectional diagram of the borehole layout is attached. Figure 1 As shown in the attached plan view of the borehole layout. Figure 2 As shown, the technical parameters for drilling from top to bottom are shown in Table 1.

[0071] Step 2: Excavate parallel return airway and transport roadway along the strike of the first mining protective layer (i.e., coal seam 13-1). During the excavation process, adopt the measures of simultaneous excavation and drainage combined with advance discharge borehole anti-outburst measures.

[0072] like Figure 4 As shown, the steps for preventing borehole outbursts by combining excavation and extraction with advance drainage are as follows:

[0073] Step 2-1: Conduct advance drainage boreholes directly in front of the tunneling face to relieve pressure and release gas;

[0074] Step 2-2: Drilling sites are set up on both sides of the roadway 5m behind the tunneling face. The drilling sites are set up diagonally along the tunneling direction to control the coal body within the tunneling influence range in order to intercept gas. Each group of drilling sites should be arranged alternately on both sides of the coal roadway. In each group of drilling sites, 12 extraction boreholes are arranged along the tunneling direction, that is, 6 boreholes are arranged in each of the left and right drilling sites. The distance from the starting position to the ending position of the borehole in the tunneling direction is 60m. The distances from the ending position of the borehole to the center line of the tunneling are 2m, 6m, 10m, 14m, 18m, and 20m respectively.

[0075] The discharge borehole in step 2-1 and the pre-extraction borehole in step 2-2 adopt a high-speed spiral drilling process. The high-speed spiral drilling speed is greater than or equal to 400 r / min and less than or equal to 800 r / min (in this embodiment, the speed of this step is 400 r / min). The drilling process adopts dry drilling. During the drilling process, airflow is circulated to the drill bit to drive the drill cuttings out and cool the drill bit.

[0076] Step 3: Pre-extraction of the coal seam between the return airway and the transport roadway using in-seam drilling, as shown in the attached diagram. Figure 5 As shown, the boreholes are arranged vertically to the transport roadway and along the coal seam, with a borehole spacing of 3 to 4 meters.

[0077] Table 4: Technical Parameters for Drilling Layout

[0078]

[0079] In steps (1) and (2) above, the high-speed spiral drilling process uses a high-speed spiral slag removal drilling machine for drilling. The high-speed spiral slag removal drilling machine includes a traveling device, a double-headed motor fixed on the traveling device, a rotating rod 30 connected to the double-headed motor, and a drill bit connected to the end of the rotating rod.

[0080] As attached Figure 3As shown, the dual-head motor includes a housing 11, end caps bolted to both ends of the housing 11, a stator 14 fixed to the inner wall of the housing 11, and an external output shaft 21 rotatably connected to the end caps via bearings. A rotor 15 corresponding to the stator 14 is mounted on the external output shaft 21. The external output shaft 21 is a hollow cylindrical shape, and an inner output shaft 22 is provided inside the external output shaft 21. The inner output shaft 22 is coaxially arranged with the external output shaft 21 and supported by a slip ring 33, thereby allowing the inner output shaft 22 to rotate relative to the external output shaft 21. One end of the inner output shaft 22 and the outer output shaft 21 is the transmission end, and the other end is the output end. The transmission ends of the inner output shaft 22 and the outer output shaft 21 are driven by the planetary gear train structure 23. Specifically, the sun gear of the planetary gear train structure 23 is fixed to the inner output shaft 22, the gear ring is fixed to the inner wall of the outer output shaft 21, the planet carrier is directly integrated into the left end cover 12, and the planet gears are rotatably connected to the left end cover 12 and mesh with the sun gear and the gear ring respectively.

[0081] Rotation of rotor 15 directly drives rotation of external output shaft 21. Through the transmission of planetary gear train 23, inner drive shaft reverses direction relative to outer drive shaft. An exhaust channel 35 is formed between inner and outer drive shafts, and several through holes parallel to the axial direction are provided on slip ring 33. An exhaust port is provided on left end cover 12 corresponding to exhaust channel 35, thus making the two ends of exhaust channel 35 interconnected. Furthermore, axial flow fan blades 38 are welded to the outer circumference of inner drive shaft, thereby creating an airflow flowing to the left within exhaust channel 35 when inner drive shaft rotates.

[0082] The rotating rod 30 includes an inner rod 32 and an outer rod 31. The outer rod 31 is sleeved outside the inner rod 32 and coaxially arranged. The inner rod 32 and the outer rod 31 are also connected by a slip ring 33, thus forming an exhaust channel 35 between the inner rod 32 and the outer rod 31. The slip ring 33 has several through holes in its circumferential direction, so that the exhaust channel 35 is connected front and back. The drill bit is pinned to the end of the outer rod 31 of the rotating rod 30, thus forming a fixed connection between the drill bit and the outer rod 31. A receiving interface is provided at the center of the drill bit connection end, so that the end of the inner rod 32 can be inserted into the receiving interface, and the inner rod 32 and the receiving interface are rotatably connected. The receiving interface extends through to the cutting end of the drill bit and communicates with the outside. An air inlet 34 is provided on the central axis of the inner rod 32. During drilling, air can be supplied to the drill bit through the air inlet 34. An air intake duct 34 is also provided on the central axis of the inner output shaft 22, and the shaft end of the inner output shaft 22 passes through the left end cover 12 of the dual-head motor to connect with the air supply unit.

[0083] The rotating rod 30 can be connected to the inner and outer output shafts 21. Specifically, the output ends of the inner and outer output shafts 21 are provided with bearing interfaces, and the side walls of these bearing interfaces are provided with spline grooves. One end of the inner rod 32 and the outer rod 31 are plug-in ends that can be inserted into the bearing interfaces of the inner output shaft 22 and the outer output shaft 21 respectively to form a spline connection, thereby transmitting the rotation of the outer output shaft 21 and the inner output shaft 22 to the outer rod 31 and the inner rod 32. To prevent the outer rod 31 and the inner rod 32 from shifting axially, the outer wall of the inner rod 32 and the inner wall of the outer rod 31 are provided with limiting steps on both sides of the slip ring 33. The limiting steps can be composed of multiple circumferentially evenly distributed limiting pins or C-shaped retaining rings embedded in the groove. At the same time, to ensure the reliability of the connection between the outer output shaft 21 and the outer rod 31, a pin can be provided that passes through the outer output shaft 21 and the outer rod 31.

[0084] To allow for the extension of the rotating rod 30, one end of the rotating rod 30 is configured as a plug-in end and the other end as a receiving end, enabling the rotating rod 30 to be connected to other rotating rods 30 in the same way as the inner and outer output shafts 21 of the rotating rod 30 described above. Furthermore, the rotating rod 30 directly connected to the drill bit only has a plug-in end, with the other end connected to the drill bit. An axial flow fan blade 38 is also welded onto the inner rod 32 of the rotating rod 30 to create an axially flowing airflow within the exhaust channel 35 inside the rotating rod 30. To reduce wear during the rotation of the inner rod 32 and the outer rod 31, the slip ring 33 is made of graphite.

[0085] A spiral groove is provided on the outer surface of the outer rod 31 of the rotating rod 30 to discharge the debris formed during drilling. Secondly, an air hole 36 is provided on the outer rod 31, penetrating the side wall of the outer rod 31. The air hole 36 is connected to the exhaust channel 35. A filter screen 37 is welded to the end of the air hole 36 near the exhaust channel 35 to prevent debris from entering the exhaust channel 35.

[0086] The working principle of the high-speed spiral slag discharge drilling machine during the drilling process is as follows:

[0087] During drilling, the dual-head motor drives the rotating rod 30 and the drill bit to rotate forward. The rotation of the drill bit breaks the coal seam and propels the drill forward, while the spiral grooves on the surface of the outer rod 31 discharge debris. Simultaneously, the left end of the inner output shaft 22 is connected to an air supply unit (the inner output shaft 22 and the air supply unit are connected by a rotary joint), allowing airflow to be introduced to the drill bit to cool it down. Furthermore, when the airflow is discharged, it can blow away debris around the drill bit, thereby increasing the drilling rate.

[0088] The rotation of the inner rod 32 drives the axial flow fan blade 38 to rotate, thereby forming an airflow from the drill bit end to the dual-head motor end in the exhaust channel 35, thus creating wind pressure in the exhaust channel 35. During the drilling process, this wind pressure causes the external airflow to enter the exhaust channel 35 through the air hole 36 and finally exit from the exhaust port on the left end cover 12. A guide pipe can be installed at the exhaust port to discharge the airflow to a designated location, preventing the gas generated during the drilling process from leaking into the working space.

[0089] Secondly, during drilling, a portion of the rotating rod 30 is located outside the borehole. Gas encounters less resistance when passing through this portion into the exhaust channel 35, making it easier for external air to enter. Since methane gas is primarily generated within the coal seam, the portion of the rotating rod 30 outside the borehole can be covered with paper to minimize external airflow into the exhaust channel 35 during drilling. Once the rotating rod 30 enters the borehole, debris will break the paper, allowing airflow from inside the borehole to enter the exhaust channel 35.

[0090] In addition, during the drilling process, the rotating rod 30 will also drive the debris to rotate, so that the debris has a certain centrifugal tendency to move outward, thereby preventing the debris from clogging the pores 36.

[0091] Example 2:

[0092] As attached Figure 5 Appendix Figure 6 As shown, the difference between Embodiment 1 and Embodiment 2 is that in Embodiment 2, the air hole 36 is a strip-shaped hole, and an exhaust module 40 is installed inside the strip-shaped hole. The exhaust module 40 includes a winding block 42 and a vibrating block 44 slidably connected inside the winding block 42. The outer periphery of the winding block 42 is provided with a winding groove, and a coil 43 is wound in the winding groove. A conical hole is provided at the center of the winding block 42. The vibrating block 44 is provided with a conical end that mates with the conical hole. The two ends of the vibrating block 44 are slidably connected to the winding block 42, and the vibrating block 44 is provided with a hole 45. The reciprocating vibration of the vibrating block 44 can cause the conical end to engage and disengage with the conical hole, thereby causing the incoming debris to vibrate, and the centrifugal force can prevent the debris from clogging the hole. In addition, an air guide groove is provided on the conical surface of the conical end of the vibrating block 44, so that even when the conical hole and the conical end are engaged, the airflow can still flow through the air guide groove.

[0093] A filter screen is provided on the side of the winding block 42 facing the inner rod 32, and compression springs are provided on the sides of the vibrating block 44 facing the outer side of the outer rod 31 at both ends. The compression springs are made of shape memory alloy, so that the vibrating block 44 forms an oscillator state. A permanent magnet 41 is fixed on the inner rod 32 at the position corresponding to the winding block 42. During the rotation of the outer rod 31, the coil 43 cuts the magnetic field lines, thereby forming an induced current in the coil 43 and raising its temperature. As the temperature rises, the compression springs elongate, increasing their stiffness. That is, during the drilling process, when the outer rod 31 is at a low speed, the coil 43 generates little heat, and the compression springs are in a shorter contracted state, so the conical hole is closed to avoid blockage. As the speed increases, the temperature of the coil 43 rises, the compression springs elongate, and a gap is formed between the conical end of the vibrating block 44 and the conical hole. At the same time, the amplitude and frequency of the vibration of the vibrating block 44 driven by the coil 43 increase, thereby preventing the conical hole from becoming blocked.

[0094] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for laying out a mine gas extraction drilling site and a borehole, characterized in that, Comprising the following steps: Step 1: After determining the first mining protective layer, the roadway is excavated along the horizontal direction to the protective layer, and the gas area of the coal uncovering face is prevented from outburst by using the through-hole drilling to pre-drain the stone door in the process of excavation; The through-hole drilling to pre-drain the stone door in the process of excavation; Step 1-1: According to the coal seam inclination, the roadway profile line of the roadway uncovering coal at the excavation direction is determined; Step 1-2: The drilling field should be implemented before the minimum normal distance of 7m from the coal seam of the coal uncovering face, and the starting position of the drilling field should be at the center of the well and roadway; Step 1-3: The control range of the drilling field is at least 12m outside the roadway profile line of the roadway uncovering coal, the final hole spacing is 3-4.0m, and the drilling length is 0.5-0.8m through the coal seam to the roof; Step 1-4: The drilling is completed by using the high-speed spiral drilling process, the rotation speed of the high-speed spiral drilling is greater than or equal to 400r / min and less than or equal to 800r / min, and the dry drilling is used in the drilling process; Step 2: The return airway and the transportation roadway are excavated along the strike of the first mining protective layer, and the outburst prevention measures of the pre-drainage drilling are combined with the advanced discharge drilling in the process of excavation; The outburst prevention measures of the pre-drainage drilling combined with the advanced discharge drilling are as follows: Step 2-1: The advanced discharge drilling is taken in front of the excavation face; Step 2-2: The drilling field is arranged on the two sides of the roadway behind the excavation face, and the pre-drainage drilling is taken in the affected range of the excavation by the drilling field along the excavation direction; The pre-drainage drilling in step 2-2 and the discharge drilling in step 2-1 adopt the high-speed spiral drilling process, the rotation speed of the high-speed spiral drilling is greater than or equal to 400r / min and less than or equal to 800r / min, and the dry drilling is used in the drilling process; Step 3: The coal body between the return airway and the transportation roadway is pre-drained by using the bedding drilling; In steps 1 and 2, the high-speed spiral drilling process uses a high-speed spiral deslagging drilling machine to drill; the high-speed spiral deslagging drilling machine comprises a walking device, a double-head motor fixed on the walking device, a rotating rod connected with the double-head motor, and a drill bit connected to the end of the rotating rod; The rotating rod comprises an inner rod and an outer rod, the outer rod is coaxially arranged outside the inner rod, and the inner rod and the outer rod are connected through a slip ring to form an exhaust passage therebetween; the slip ring is provided with a through hole in the circumferential direction to connect the exhaust passage in front and back; the drill bit is fixed at the end of the outer rod of the rotating rod; the drill bit is provided with a receiving port in the center, so that the end of the inner rod can be inserted into the receiving port, and the receiving port penetrates the cutter end of the drill bit and communicates with the outside; an air inlet is arranged on the central axis of the inner rod, and air can be supplied to the drill bit through the air inlet during drilling; The outer surface of the outer rod of the rotating rod is provided with a spiral groove, and the outer rod is provided with an air hole penetrating the side wall of the outer rod, the air hole communicates with the exhaust passage, and the end of the air hole close to the exhaust passage is welded with a filter screen; the inner rod of the rotating rod is welded with an axial flow fan blade, and the rotation of the inner rod forms an axial flow in the exhaust passage in the rotating rod; The double-head motor can drive the inner rod and the outer rod of the rotating rod to rotate in opposite directions; During the drilling process, part of the rotating rod outside the drilling hole is covered with paper sheets and is adhered.

2. The layout method of a mine gas extraction drilling field and a borehole according to claim 1, characterized in that, In the steps 1-3, the extraction radius is 2 m, the final hole spacing is 4.0 m, and the drilling diameter is 75 mm.

3. The layout method of mine gas extraction drilling field and borehole according to claim 2, characterized in that: In the step 2, the drilling field is arranged at the two sides of the roadway 5 m behind the tunneling face, 12 extraction boreholes are arranged in each drilling field along the tunneling direction, 6 boreholes are arranged in the left and right drilling fields respectively, the distance from the starting position of the borehole to the final position of the borehole in the tunneling direction is 60 m, and the distance from the final position of the borehole to the center line of the roadway tunneling is 2 m, 6 m, 10 m, 14 m, 18 m and 20 m respectively.

4. The layout method of mine gas extraction drilling field and borehole according to claim 3, characterized in that: In the step 1-4, the rotation speed of the high-speed spiral drilling is 600 r / min.

5. The layout method of the mine gas extraction drilling field and the borehole according to claim 4, characterized in that: In the step 2, the rotation speed of the high-speed spiral drilling is 400 r / min.

6. The layout method of mine gas extraction drilling field and borehole according to claim 5, characterized in that: The double-head motor comprises a shell, end covers fixed on both ends of the shell by bolts, a stator fixed on the inner wall of the shell, and an outer output shaft rotatably connected to the end cover, and a rotor is fixed on the outer output shaft; the outer output shaft is a hollow cylinder, and an inner output shaft is arranged in the outer output shaft, and the inner output shaft is coaxially arranged with the outer output shaft and is connected to the inner output shaft through a slip ring; one end of the inner output shaft and the outer output shaft is a transmission end, and the other end is an output end, the transmission end is transmitted through a planetary gear system structure, and the transmission end of the inner output shaft extends from the left end cover; An exhaust passage is formed between the inner transmission shaft and the outer transmission shaft, and a through hole parallel to the axial direction is arranged on the slip ring, and an exhaust port is arranged on the left end cover corresponding to the exhaust passage; the output end extends from the right end cover, and an air inlet is arranged on the central axis of the inner output shaft; the output end of the outer output shaft is connected with the outer rod, and the output end of the inner output shaft is connected with the inner rod.

7. The layout method of mine gas extraction drilling field and borehole according to claim 6, characterized in that: The air hole is a strip-shaped hole, and an exhaust module is mounted in the strip-shaped hole; the exhaust module comprises a winding block and a vibrating block slidably connected in the winding block; a winding groove is arranged on the outer periphery of the winding block, a coil is wound in the winding groove, a tapered hole is arranged at the center of the winding block, a tapered end is arranged on the vibrating block and matched with the tapered hole, the two ends of the vibrating block are slidably connected with the winding block, and a hole is arranged on the vibrating block; the vibrating block reciprocates to make the tapered end matched with or separated from the tapered hole. A filter screen is arranged on the side of the winding block facing the inner rod, and a compression spring is arranged on the side surface of the vibrating block facing the outer side of the outer rod, so that the vibrating block forms a vibrator state, and the compression spring is made of a memory alloy; a permanent magnet is fixed on the inner rod corresponding to the position of the winding block.

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