Gas control method for super-long stope face of super-thick coal seam

Abstract

The embodiment of the invention provides a gas control method for an ultra-long stope face of an ultra-thick coal seam. The method comprises the following steps that S1, a first extraction roadway is excavated in the area, close to an air return roadway, of a roof rock stratum of an upper caving zone of a coal seam corresponding to the ultra-long stope face of the ultra-thick coal seam; s2, after tunneling of the first extraction roadway is completed, a through hole is formed between the goaf and the extraction roadway in a penetrating mode so that the cut roadway can communicate with the extraction roadway through the through hole, the goaf, the through hole and the extraction roadway communicate to form a first gas discharge passage, and gas in the gas discharge passage is extracted in a negative pressure extraction mode; and S3, the working face is stoped, the step S1 to the step S2 are repeated, and a plurality of gas discharge passages are formed until stoping is finished. Therefore, the gas prevention and control method for the super-long stope face of the super-thick coal seam has the advantage that the mining safety is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mines, and in particular to a gas prevention and control method for an ultra-long mining face in an extra-thick coal seam. Background Art

[0002] During coal caving in fully-mechanized top-coal caving faces in extra-thick coal seams, large amounts of coal are rapidly crushed, releasing large amounts of gas. This is the primary source of gas emission from the working face. This is particularly true for mining in extra-long working faces. The increased amount of coal left in the goaf further increases the risk of spontaneous combustion. Due to the large amount of gas emission during mining, conventional full-face ventilation mining methods are not suitable for gas control in the extra-thick coal seam fully-mechanized top-coal caving and extra-long working faces, making gas over-limit issues very likely to occur. Furthermore, as the working face lengthens, nitrogen injection in the middle and rear of the extra-long working face has limited impact. Therefore, when mining is slowed or stopped, the risk of spontaneous combustion in the goaf increases rapidly, significantly impacting safety during mining. Summary of the Invention

[0003] The present invention aims to address, at least to some extent, one of the technical problems in the related art. To this end, embodiments of the present invention provide a method for gas prevention and control in an ultra-long mining face in an extra-thick coal seam. This method for gas prevention and control in an ultra-long mining face in an extra-thick coal seam has the advantage of improving safety during mining.

[0004] The gas prevention and control method for an ultra-long mining face in an extra-thick coal seam according to an embodiment of the present invention comprises the following steps. The thickness of the extra-thick coal seam is greater than 10 meters, the length of the ultra-long mining face exceeds 300 meters, a U-shaped ventilation system is employed during mining, and multiple goafs are formed during excavation of intake and exit air lanes, cut lanes, and return air lanes.

[0005] S1, first excavating the first extraction tunnel roughly parallel to the return air tunnel 2 in the roof rock layer of the upper collapsed zone of the coal seam corresponding to the ultra-long working face of the extra-thick coal seam and in the offset area with the return air tunnel;

[0006] S2, after the excavation of the first drainage roadway is completed, a conducting hole is drilled between the goaf and the drainage roadway to connect the cut roadway and the drainage roadway through the conducting hole, the goaf, the conducting hole and the drainage roadway are connected to form a first gas discharge passage, and the gas in the gas discharge passage is extracted by negative pressure extraction;

[0007] S3, recover the working face and repeat steps S1 to S2 to form multiple gas exhaust passages until recovery is completed.

[0008] The gas prevention and control method for the extra-thick coal seam and the extra-long mining face of the embodiment of the present invention is to excavate multiple extraction tunnels roughly parallel to the return air tunnel in the roof rock layer of the upper collapse zone of the coal seam corresponding to the extra-thick coal seam and the extra-long working face, and set a conductive hole between the goaf and the extraction tunnel to connect the cutting tunnel and the extraction tunnel to form a gas discharge passage, and use negative pressure extraction to extract the gas in the gas discharge passage. In addition, the gas in the goaf and the nearby rock layer can be discharged in time, thereby improving the safety of mining. Compared with the traditional full-section ventilation method, this local extraction method can effectively reduce the total resistance of the ventilation system, making ventilation smoother and more efficient, more significantly reducing the amount of gas accumulated in the goaf and reducing the risk of gas explosion, thereby improving the safety of mine operations. It also avoids the problem of gas being diluted during the flow process in traditional methods, and also improves the concentration and efficiency of gas extraction.

[0009] At the same time, forming multiple gas emission pathways can cover a wider area, ensuring that gas in the entire goaf and surrounding areas can be effectively extracted, further reducing the amount of gas accumulated in the goaf and the risk of gas explosion.

[0010] In addition, the use of negative pressure to extract gas from the extraction tunnel can create a relatively negative pressure environment in the air intake tunnel, cutting tunnel and return air tunnel connected to it, which helps to guide fresh air into the working face better, improves the ventilation conditions of the entire working face, further reduces gas accumulation, and further improves the safety of mine operations.

[0011] Therefore, the gas prevention and control method for ultra-thick coal seams and ultra-long mining faces according to the embodiments of the present invention has the advantages of greatly reducing explosion hazards caused by gas accumulation and improving safety during mining.

[0012] In some embodiments, an extraction pipeline is laid in the extraction tunnel, and the extraction pipeline is connected to a gas extraction pump to extract gas from the extraction tunnel.

[0013] In some embodiments, 2 to 4 extraction pipelines are arranged in each extraction tunnel, and the diameter of the extraction pipeline is 300 mm to 400 mm.

[0014] In some embodiments, the extraction pipeline is laid in the stable rock layer of the upper collapse zone of the coal seam at the working face.

[0015] In some embodiments, the extraction pipeline extends into the extraction tunnel for a length of not less than 10 m.

[0016] In some embodiments, the distance between two adjacent extraction tunnels is 60m to 70m.

[0017] In some embodiments, the cross-sectional dimensions of each of the extraction tunnels are not less than 4m×3m.

[0018] In some embodiments, the first extraction tunnel is excavated in the roof rock layer between the return air tunnel and the intake air tunnel at a position 20m to 30m away from the return air tunnel.

[0019] In some embodiments, the negative pressure of each extraction tunnel is not less than -5 kPa, and the extraction flow rate of each extraction tunnel is not less than 1000 m 3 / min.

[0020] In some embodiments, a bundle pipe is laid in the extraction tunnel to monitor the extraction gas conditions.

[0021] In some embodiments, each of the extraction tunnels is a dead-end tunnel, and the tunnel entrance of the dead-end tunnel is blocked with a closed wall to form a sealed tunnel.

[0022] In some embodiments, there are multiple sealed walls, and the distance between adjacent sealed walls is greater than 4m.

[0023] In some embodiments, the thickness of the sealed wall is greater than 1 m, and fly ash slurry is filled between adjacent sealed walls to form a fly ash layer.

[0024] In some embodiments, a group of directional drill holes are constructed in the middle and upper part of the super-long working face, and the directional drill holes are used to extract gas from the goaf. If the super-long working face advances slowly or stops, nitrogen, mud or gel is injected into the goaf through the directional drill holes to prevent spontaneous combustion in the goaf.

[0025] In some embodiments, the diameter of the directional drilled holes is not less than 120 mm, the distance between adjacent directional drilled holes is not less than 5 m, and the number of directional drilled holes in each group is not less than 5. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the closed construction and extraction pipeline layout of an embodiment of the present invention.

[0027] Figure 2 It is a cross-sectional view of the extraction tunnel and directional drilling arrangement position of an embodiment of the present invention.

[0028] Figure 3 It is a schematic diagram of the plan layout of the extraction tunnel and directional drilling in an embodiment of the present invention.

[0029] Reference numerals:

[0030] Working face 100; roof rock layer 200;

[0031] Inlet tunnel 1;

[0032] Return air channel 2;

[0033] Goaf 3;

[0034] Extraction tunnel 4;

[0035] Extraction pipeline 5;

[0036] via 6;

[0037] Confined wall 7;

[0038] Directional drilling 8;

[0039] Fly ash layer 9;

[0040] Detection tube bundle 10. DETAILED DESCRIPTION

[0041] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0042] Reference below Figure 1-Figure 3 A gas prevention and control method for an extra-long mining face 100 in an extra-thick coal seam according to an embodiment of the present invention is described. The extra-thick coal seam is greater than 10 meters thick, and the extra-long mining face 100 is greater than 300 meters long. During mining, a U-shaped ventilation system is employed. During excavation, multiple cut lanes are excavated to form multiple goafs 3, including an intake tunnel 1, a cut tunnel, and a return tunnel 2.

[0043] The gas prevention and control method for an ultra-long mining face 100 in an extra-thick coal seam according to an embodiment of the present invention comprises the following steps:

[0044] S1, excavating a first extraction roadway 4 in the roof rock layer 200 of the upper collapsed zone of the coal seam corresponding to the extra-thick coal seam and the extra-long working face 100, close to the offset area of the return air lane 2; and the first extraction roadway 4 is substantially parallel to the return air lane 2;

[0045] S2. After the excavation of the first drainage roadway 4 is completed, a guide hole 6 is drilled between the goaf 3 and the drainage roadway 4 to connect the cutting roadway and the drainage roadway 4 through the guide hole 6. The goaf 3, the guide hole 6, and the drainage roadway 4 are connected to form a first gas discharge path. The gas in the gas discharge path is extracted by negative pressure extraction. Ensure that the roadway can drain the goaf in the initial stage of mining (support is provided in accordance with relevant requirements during the excavation of the drainage roadway 4);

[0046] S3, mining the working face 100, and repeating steps S1 to S2 to form multiple gas exhaust passages until mining is completed.

[0047] The gas prevention and control method for the ultra-long mining face 100 in the ultra-thick coal seam according to the embodiment of the present invention is to excavate a drainage tunnel 4 roughly parallel to the return air tunnel 2 in the roof rock layer 200 of the upper collapsed zone of the coal seam corresponding to the ultra-thick coal seam ultra-long mining face 100, and set a conducting hole 6 between the goaf 3 and the drainage tunnel 4 to connect the cutting tunnel and the drainage tunnel 4 to form a gas discharge passage, and use negative pressure extraction to extract the gas in the gas discharge passage. In this way, the gas in the goaf 3 and the nearby rock layer can be discharged in time, thereby improving the safety of mining. Compared with the traditional full-section ventilation method, this local extraction method can effectively reduce the total resistance of the ventilation system, making ventilation smoother and more efficient, more significantly reducing the amount of gas accumulated in the goaf 3 and reducing the risk of gas explosion, thereby improving the safety of mine operations. It also avoids the problem of gas dilution during the flow process in traditional methods and improves the concentration and efficiency of gas extraction.

[0048] At the same time, multiple gas exhaust pathways can cover a wider area, ensuring that gas in the entire goaf 3 and surrounding areas can be effectively extracted, further reducing the amount of gas accumulated in the goaf 3 and the risk of gas explosion.

[0049] In addition, the use of negative pressure to extract the extraction tunnel 4 can form a relatively negative pressure environment in the air intake tunnel 1, cutting tunnel and return air tunnel 2 connected to it, which helps to guide fresh air to better enter the working face 100, improve the ventilation conditions of the entire working face 100, reduce the accumulation of toxic and harmful gases such as gas, and further improve the safety of mine operations.

[0050] Therefore, the gas prevention and control method for the ultra-thick coal seam ultra-long mining working face 100 according to the embodiment of the present invention has the advantages of greatly reducing the explosion hazard caused by gas accumulation and improving safety during mining.

[0051] As mining progresses, the length of the extraction tunnel 4 will also decrease due to the collapse of the working face. Since no coal is placed in the initial mining phase, in order to ensure that the two extraction tunnels 4 are connected to the cutting tunnel, a guide hole is constructed in the cutting tunnel before the working face is mined, thereby ensuring that the tunnel can drain the gas from the goaf through the guide hole in the initial mining phase. For example, Figure 1 and Figure 2 As shown, there are two extraction tunnels 4.

[0052] like Figure 1 As shown, 2 to 4 extraction pipelines 5 are arranged in each extraction tunnel 4, and the diameter of the extraction pipeline 5 is 300 mm to 400 mm.

[0053] The gas prevention and control method for an extra-long mining face 100 in an extra-thick coal seam according to an embodiment of the present invention limits the number of extraction pipelines 5 within each extraction roadway 4. This method, on the one hand, avoids the problem of excessive gas due to delayed gas extraction caused by too few extraction pipelines 5, and on the other hand, avoids the problem of excessive mining costs caused by too many extraction pipelines 5. Thus, this gas prevention and control method helps reduce mining costs and prevents gas accumulation.

[0054] In addition, the diameter of the extraction pipeline 5 is set to 300 mm to 400 mm.

[0055] The gas prevention and control method for an ultra-long mining face 100 in an extra-thick coal seam according to an embodiment of the present invention limits the diameter of the extraction pipeline 5. This method, on the one hand, avoids the problem of an overly large diameter of the extraction pipeline 5, which increases construction difficulty and labor costs. On the other hand, it avoids the problem of an undersized diameter, which limits the gas flow rate and results in incomplete extraction, which fails to meet the requirements for efficient extraction.

[0056] Optionally, 2, 3 or 4 extraction pipelines 5 may be arranged in each extraction tunnel 4. For example, Figure 1 As shown in FIG, four extraction pipelines 5 are provided in each extraction tunnel 4. Furthermore, the four extraction pipelines 5 are staggered in the vertical direction. Thus, the staggered extraction pipelines 5 help cover a wider extraction area, helping to ensure that gas in the entire goaf 3 and surrounding areas can be effectively extracted.

[0057] Optionally, the diameter of the extraction pipeline 5 is 300 mm, 310 mm, 320 mm, 330 mm, 340 mm, 350 mm, 360 mm, 370 mm, 380 mm, 390 mm or 400 mm.

[0058] like Figure 2 As shown, a drainage tunnel 4 is laid in the stable rock formation in the upper collapsed zone of the coal seam at the working face 100. Laying the drainage tunnel 4 in a stable rock formation generally makes drilling and support operations easier than excavating the drainage tunnel 4 in a loose or unstable coal seam, reduces the possibility of deformation of the drainage tunnel 4, and reduces the need for subsequent maintenance.

[0059] Furthermore, the extraction pipeline 5 extends into the extraction tunnel 4 for a length of not less than 10m. By reasonably setting the length of the extraction pipeline 5 extending into the extraction tunnel 4, on the one hand, it is possible to avoid the extraction pipeline 5 extending into the extraction tunnel 4 for a length that is too long, resulting in an increase in the total gas pressure loss of the system, and a longer pipeline will cause the gas flow rate to decrease, which can easily lead to a laminar flow state in a local area, thereby reducing the efficiency of the entire extraction system. On the other hand, it is possible to avoid the extraction pipeline 5 extending into the extraction tunnel 4 for a length that is too short, resulting in some gas not being effectively extracted, increasing the risk of gas accumulation in the goaf 3. If the pipeline length is not enough to connect all necessary extraction points, it may cause the gas concentration in certain areas to exceed the standard, affecting safe production. Therefore, the reasonable setting of the extraction pipeline 5 can improve the extraction efficiency and enhance the safety of the operation.

[0060] Optionally, a portion of the extraction pipeline 5 extending into the extraction tunnel may be circumferentially provided with a plurality of air inlet holes to increase the smoothness of the gas extraction pipeline 5 .

[0061] The distance between two adjacent extraction tunnels 4 is 60m to 70m.

[0062] The gas prevention and control method for an extra-long mining face 100 in an extra-thick coal seam according to an embodiment of the present invention, by reasonably limiting the spacing between adjacent extraction tunnels 4, avoids the risk of gas accumulation, which may occur when the spacing is too large, resulting in ineffective extraction in certain areas. This can lead to localized excessive gas concentrations, impacting safe production, and also avoids the problem of increased initial construction costs, resulting from the need for more material for excavation and support, caused by a narrow spacing between adjacent extraction tunnels 4.

[0063] Optionally, the distance between two adjacent extraction tunnels 4 can be 60m, 61m, 62m, 63m, 64m, 65m, 66m, 67m, 68m, 69m and 70m.

[0064] Optionally, the gas prevention and control method for the ultra-long mining face 100 of the extra-thick coal seam according to the embodiment of the present invention may further include setting a detection bundle pipe and a grouting pipe in the extraction tunnel 4 .

[0065] Alternatively, as Figure 2 As shown, the gas prevention and control method for an extra-thick coal seam and an extra-long mining face 100 according to an embodiment of the present invention can also include installing a valve near the outlet of the extraction pipeline 5. A bundled pipe is installed within the extraction roadway 4 to monitor the extracted gas. This prevents gas exceeding the limit due to untimely extraction.

[0066] The cross-sectional dimensions of each extraction tunnel 4 are not less than 4m×3m. In other words, the width of each extraction tunnel 4 is 4m; the height of each extraction tunnel 4 is 3m.

[0067] In the roof rock layer 200 between the return air lane 2 and the intake air lane 1, a first extraction tunnel 4 is excavated at a position 220m to 30m away from the return air lane. It can be understood that the distance between the return air lane 2 and the first extraction tunnel 4 is 20m to 30m.

[0068] During mining at working face 100, the roadway is connected to goaf 3 and drained from goaf 3. The first drainage roadway 4 primarily controls excessive gas in the upper corner, while the second drainage roadway 4 targets gas accumulation areas in the middle and lower parts of working face 100. This effectively reduces gas concentrations in working face 100, the upper corner, and the return air lane 2.

[0069] The drainage negative pressure of each drainage tunnel 4 is not less than -5kPa, and the drainage flow rate of each drainage tunnel 4 is not less than 1000m 3 / min. This further improves the thoroughness of gas extraction in the extraction tunnel 4 and further enhances mining safety.

[0070] Each extraction tunnel 4 is a dead-end tunnel, and the tunnel entrance of the dead-end tunnel is blocked by a closed wall 7 to form a sealed tunnel, providing a closed space and negative pressure environment for gas extraction.

[0071] like Figure 1 As shown, there are multiple sealed walls 7, and the distance between two adjacent sealed walls 7 is greater than 4m. This helps to further improve the sealing of the extraction tunnel 4. For example, Figure 1 As shown, there can be two sealing walls 7, which helps to improve the sealing performance of the extraction tunnel 4.

[0072] The thickness of the sealed wall 7 is greater than 1 m, and fly ash slurry is filled between adjacent sealed walls 7 to form a fly ash layer 9, which helps to further improve the sealing performance of the extraction tunnel 4.

[0073] Furthermore, the thickness of the fly ash layer 9 is greater than 4 m.

[0074] A group of directional drill holes 8 are constructed in the middle and upper part of the super-long working face 100, and the directional drill holes 8 are used to extract gas from the goaf 3. If the super-long working face 100 advances slowly or stops advancing, casing is lowered into the directional drill holes, and nitrogen, mud or gel is injected into the goaf 3 through the directional drill holes 8 to prevent spontaneous combustion in the goaf 3.

[0075] Furthermore, the diameter of the directional drill hole 8 is not less than 120 mm.

[0076] The gas control method for an ultra-long mining face 100 in an extra-thick coal seam according to an embodiment of the present invention limits the diameter of the directional drill hole 8. A larger diameter of the directional drill hole 8 results in a higher gas flow rate, which helps increase the gas extraction rate per unit time. Furthermore, a larger diameter directional drill hole 8 facilitates subsequent operations such as hole cleaning, unblocking, and inserting monitoring equipment, thereby extending the service life of the directional drill hole 8.

[0077] Furthermore, the drilling distance between adjacent directional drill holes 8 is not less than 5 m.

[0078] The gas prevention and control method for the ultra-long mining face 100 of the extra-thick coal seam of the embodiment of the present invention limits the spacing between adjacent directional drill holes 8. On the one hand, overly dense arrangement will lead to "negative pressure interference" between the boreholes, that is, the extraction of one borehole affects the effect of the adjacent boreholes. Maintaining a spacing of more than 5m helps each borehole to independently exert its maximum extraction capacity. Reasonable spacing can ensure that the gas in the entire target area (such as the goaf 3 and the fracture zone) can be effectively extracted to prevent local gas accumulation.

[0079] Each group of directional boreholes 8 must consist of no fewer than five. Simultaneous operation of multiple boreholes forms an effective "extraction network," enhancing overall extraction efficiency and improving system stability. This prevents blockage or failure of individual boreholes while maintaining adequate extraction capacity in other boreholes, ensuring continuity of gas control efforts.

[0080] In some embodiments, the diameter of the directional drill holes 8 is set to 150 mm, the spacing between adjacent directional drill holes 8 is set to 8 m, and the number of directional drill holes 8 in each group is 10. Furthermore, the gas prevention and control method for the ultra-long mining face 100 in an extra-thick coal seam according to the embodiment of the present invention has the advantage of further improving mining quality.

[0081] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0082] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0083] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0084] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0085] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0086] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A method for preventing and controlling gas in an extra-thick coal seam and an extra-long mining face, wherein: The thickness of the extra-thick coal seam is greater than 10m, and the length of the extra-long working face exceeds 300m. During mining, a U-shaped ventilation method is adopted. During the excavation, the air intake tunnel, the cutting tunnel and the return air tunnel are driven in and out. Multiple cutting tunnels during mining form multiple goafs. It is characterized in that the gas prevention and control method includes: S1, excavating a first extraction tunnel approximately parallel to the return air lane 2 in the roof rock layer of the upper collapsed zone of the coal seam corresponding to the ultra-long working face of the extra-thick coal seam, in an area close to and offset from the return air lane; S2, after the excavation of the first drainage roadway is completed, a conducting hole is drilled between the goaf and the drainage roadway to connect the cut roadway and the drainage roadway through the conducting hole, the goaf, the conducting hole and the drainage roadway are connected to form a first gas discharge passage, and the gas in the gas discharge passage is extracted by negative pressure extraction; S3, recover the working face and repeat steps S1 to S2 to form multiple gas exhaust passages until recovery is completed.

2. The method for gas prevention and control in an ultra-thick coal seam and an ultra-long mining face according to claim 1 is characterized in that: An extraction pipeline is laid in the extraction tunnel, and the extraction pipeline is connected to a gas extraction pump to extract gas from the extraction tunnel.

3. The method for gas prevention and control in an ultra-thick coal seam and ultra-long mining working face according to claim 1 is characterized in that: 2 to 4 extraction pipelines are laid in each extraction tunnel, and the diameter of the extraction pipeline is 300 mm to 400 mm; and / or, laying the extraction pipeline in the stable rock layer of the upper collapsed zone of the coal seam at the working face; and / or, the extraction pipeline extends into the extraction tunnel for a length of not less than 10 m; and / or, the distance between two adjacent extraction tunnels is 60m to 70m; And / or, the cross-sectional size of each extraction tunnel is not less than 4m×3m.

4. The method for gas prevention and control in an ultra-thick coal seam and an ultra-long mining face according to claim 1 is characterized in that: In the roof rock layer between the return air lane and the intake air lane, the first extraction tunnel is excavated at a position 20m to 30m away from the return air lane.

5. The method for gas prevention and control in an ultra-thick coal seam and ultra-long mining working face according to claim 1 is characterized in that: The negative pressure of each extraction tunnel is not less than -5kPa, and the extraction flow rate of each extraction tunnel is not less than 1000m 3 / min; And / or, a bundle pipe is laid in the extraction tunnel to monitor the extraction gas situation.

6. The method for gas prevention and control in an ultra-thick coal seam and ultra-long mining working face according to claim 1 is characterized in that: Each of the extraction tunnels is a dead-end tunnel, and the tunnel entrance of the dead-end tunnel is blocked with a closed wall to form a sealed tunnel.

7. The method for gas prevention and control in an ultra-thick coal seam and an ultra-long mining face according to claim 6, characterized in that: There are multiple sealed walls, and the distance between adjacent sealed walls is greater than 4m.

8. The method for gas prevention and control in an ultra-thick coal seam and ultra-long mining working face according to claim 6, characterized in that: The thickness of the closed wall is greater than 1m, and fly ash slurry is filled between adjacent closed walls to form a fly ash layer.

9. The method for gas prevention and control in an ultra-thick coal seam and ultra-long mining working face according to claim 1, characterized in that: A group of directional drill holes are constructed in the middle and upper part of the super-long working face, and the directional drill holes are used to extract gas from the goaf. If the super-long working face advances slowly or stops, nitrogen, mud or gel is injected into the goaf through the directional drill holes.

10. The method for gas prevention and control in an ultra-thick coal seam and ultra-long mining working face according to claim 9, characterized in that: The diameter of the directional drilled holes is not less than 120 mm, the distance between adjacent directional drilled holes is not less than 5 m, and the number of directional drilled holes in each group is not less than 5.

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