Small-angle roof coal uncovering tunnel vault small-section coal uncovering process

Abstract

The invention relates to the technical field of tunnel construction, in particular to a small-angle roof coal uncovering tunnel vault small-section coal uncovering process which comprises the steps that S1, a stepped drill site is excavated; s2, pumping and draining holes are drilled; s3, building an extraction system; and S4, extraction operation is carried out. A stepped drill site is excavated in a limited stepped mode in the overall direction of bedding, pumping and draining holes are drilled in the mode perpendicular to a stepped drilling face, drilling holes can be evenly distributed in a target area through drilling channels with the approximately same length, and due to the fact that the directions of the drilling channels are determined, the drilling angle and depth can be rapidly determined, and the drilling efficiency is improved. The distance to a bedding surface is conveniently pre-judged, the drilling speed and pressure of a drilling machine are dynamically adjusted in advance, the construction safety is improved, the construction work amount is reduced, the construction efficiency is improved, the pore-forming rate is increased, meanwhile, a drilling channel can form small-angle intersection with the bedding surface, a pumping and draining hole can effectively make contact with more bedding gaps containing gas, and the gas drainage effect is improved. The coverage of the bedding surface area is improved, and the mining efficiency can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tunnel construction, in particular to a small-angle roof coal uncovering tunnel vault small-section coal uncovering process. BACKGROUND

[0002] In the process of gas-containing coal seam highway tunnel construction, coal seam in front of the tunnel face needs to be uncovered to improve the working face production environment and ensure the safety and smooth crossing of the tunnel through the coal seam. The coal uncovering operation needs to strictly implement the relevant regulations for outburst prevention and coal uncovering. The commonly used outburst prevention and control technology is to set up drainage holes in the tunnel construction area to drain the gas in the surrounding rock and the tunnel face.

[0003] The existing drainage hole arrangement mostly uses hydraulic punching to increase the permeability and cooperate with hole protection or radial drilling of main and auxiliary holes. However, the existing tunnel high-stress soft coal seam drilling generally has the defects of low hole forming rate, low construction efficiency, poor safety, poor adaptability, complex process and high cost.

[0004] For example, the Chinese invention patent High-speed rail tunnel low-angle coal seam high-low drilling site advanced outburst prevention and drilling drainage method (publication number CN115977721B) discloses an advanced outburst prevention and drilling drainage method using hydraulic punching to increase the permeability and cooperating with casing to protect the hole. However, this drainage method has strong dependence on equipment, needs to build a first drilling site and a second drilling site in the tunnel main hole and the flat guide, respectively, and constructs a large number of drillings to the low-angle coal seam from the first drilling site and the second drilling site. The construction cost and complexity are high, the efficiency is low, the initial construction cost is increased, and a large number of drillings with long length and high precision are needed, which has unsatisfactory application effect in high-stress soft coal seams. The drilling construction time and labor cost are high, the construction efficiency is low, and the overall construction progress is affected. The Chinese invention patent Large-section tunnel through small-angle coal seam gas drainage drilling arrangement method (publication number CN112324489B) discloses setting up flat guide hole radial drillings in the flat guide hole tunnel face and installing drainage pipelines for gas drainage. However, this drilling arrangement method needs to be based on the construction of the flat guide hole, and in high-stress soft coal seams, the excavation risk and cost of the flat guide hole are high. When the coal seam is locally thickened or thinned, the fixed drilling spacing and extension direction may also cause insufficient gas drainage in some areas and excessive drainage in other areas, affecting the stability of the coal seam and the gas control effect. SUMMARY

[0005] The purpose of the present application is to overcome the problems of low hole forming rate, low construction efficiency and poor safety of the existing tunnel high-stress soft coal seam drilling uncovering operation drainage hole drilling, and to provide a small-angle roof coal uncovering tunnel vault small-section coal uncovering process.

[0006] The application provides a small-angle roof coal uncovering tunnel vault small-section coal uncovering process, which comprises the following steps: S1, excavating a stepped drill field, wherein the stepped drill field comprises a plurality of steps arranged along the inclination of the coal seam bedding plane, the top surface of each step is arranged as an operation platform, and the vertical surface is arranged as a drilling surface; S2, drilling and pumping holes, using a drill rig to stand on the operation platform, drilling a plurality of pumping holes on the drilling surface, the pumping holes are perpendicular to the drilling surface, the axes of the adjacent pumping holes are parallel, and the pumping holes form a drilling hole arranged in an equidistant array on the target coal seam; S3, building an extraction system, connecting the pumping holes to a gas extraction system after sealing the pumping holes, and the gas extraction system is connected with a monitoring system; S4, performing extraction operation.

[0007] The small-angle roof coal uncovering tunnel vault small-section coal uncovering process can realize uniform distribution of drilling holes in the target area through drilling holes with approximately the same length, can quickly determine the drilling angle and depth, is convenient for predicting the distance to the bedding plane, can dynamically adjust the drilling speed and pressure of the drill rig in advance, improves the construction safety and reduces the construction engineering quantity, improves the construction efficiency and the hole forming rate, and the drilling hole can form a small-angle intersection with the bedding plane, so that the pumping hole can effectively contact more gas-containing bedding fissures, improves the coverage of the bedding plane area, and is beneficial to improving the mining efficiency.

[0008] Preferably, the drilling surface heights of adjacent steps are consistent, and the pumping holes have a height of 1-2 m on the drilling surface.

[0009] Preferably, the drilling direction of the pumping hole is inclined according to the inclination of the coal seam bedding plane, and the axis of the pumping hole intersects with the coal seam bedding plane at a small-angle intersection of 10-30°.

[0010] Preferably, the diameter of the pumping hole is 75-115 mm, the length of the pumping hole is 20-80 m, and the interval of the pumping hole on the target coal seam is less than or equal to 4 m.

[0011] Preferably, the inclination of the stepped drill field is parallel to the direction of the connecting line of the edges of the plurality of steps, and the inclination deviation of the stepped drill field and the inclination of the coal seam bedding plane is not more than ±5°.

[0012] Preferably, the pumping holes are arranged in the coal seam within a range of 10 m from the normal line of the excavation contour line in the length direction of 15 m on both sides of the tunnel main hole, and the pumping holes are constructed by using a crawler hydraulic tunnel drill.

[0013] Preferably, the number of the stepped drill fields is more than one.

[0014] Preferably, in S3, the hole sealing comprises pumping hole sealing by using polyurethane or M425 cement mortar, when the drainage hole is a rock hole, the hole sealing length is greater than or equal to 5m, and when the drainage hole is a coal hole, the hole sealing length is greater than or equal to 8m.

[0015] Preferably, the gas extraction system comprises an extraction station, an extraction main pipeline and an extraction branch pipeline, the extraction main pipeline is arranged overhead in the tunnel through a support frame, the extraction branch pipeline is connected with the drainage hole and the extraction main pipeline, and the extraction branch pipeline is provided with a valve.

[0016] Preferably, the monitoring system is provided with a plurality of monitoring points in the tunnel and outside the tunnel respectively, the monitoring points are equipped with automatic monitoring mechanisms and / or manual detection mechanisms, the automatic monitoring mechanisms comprise V-cone flow meters and gas concentration sensors, the manual detection mechanisms comprise detection ports and gas pipeline drainage parameter measuring instruments, and the automatic monitoring mechanisms are connected with a tunnel safety monitoring system.

[0017] Compared with the prior art, the present application has the following beneficial effects: 1. The present application provides a small-angle roof coal uncovering tunnel vault small-section coal uncovering process, a stepped drill field is excavated in a limited stepped form by conforming to the overall trend of the bedding, the drainage hole is drilled in a manner perpendicular to the step hole surface, and uniform distribution of the drill holes in the target area can be realized through drill hole passages with substantially the same length; 2. The small-angle roof coal uncovering tunnel vault small-section coal uncovering process provided by the present application can quickly determine the drilling angle and depth due to the substantially same depth and determined direction of the drill hole passages, facilitate the prediction of the distance to the bedding surface, dynamically adjust the drilling speed and pressure of the drilling machine in advance, improve the construction safety and reduce the construction engineering quantity, improve the construction efficiency, and improve the hole completion rate; 3. The small-angle roof coal uncovering tunnel vault small-section coal uncovering process provided by the present application forms a small-angle intersection between the drill hole passage and the bedding surface, so that the drainage hole can effectively contact more bedding fissures containing gas, improves the coverage of the bedding surface area, and is beneficial to improve the mining efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a flowchart of the small-angle roof coal uncovering tunnel vault small-section coal uncovering process of Example 1.

[0019] Figure 2 It is a lateral schematic view of the drainage hole drilled in the stepped drill field in Example 1.

[0020] Figure 3 It is a schematic view of the final hole state of the drainage hole in the bedding surface in Example 1.

[0021] Figure 4 Drilling diagram of the gas drainage hole described in Example 1.

[0022] Figure 5 Structure diagram of the gas drainage system described in Example 1.

[0023] Markings in the figure: 1 - operation platform, 2 - drilling surface, 3 - drainage hole, 4 - coal seam bedding surface, 5 - tunnel, 6 - drainage branch pipe, 7 - valve. DETAILED DESCRIPTION

[0024] The application will be further described in conjunction with specific embodiments. However, it should not be understood as limiting the above-mentioned subject matter of the application to the following examples only, and any technology realized based on the content of the application falls within the scope of the application.

[0025] In the description of the specific embodiments of the application, the orientation or position relationship terms such as "up", "down", "left", "right", "center", "inner", "outer" and the like appear without special instructions, which are based on the orientation or position relationship expressed in the drawings, or the orientation or position relationship when the product / equipment / device of the application is usually used. These orientation or position relationship terms are only for the convenience of describing the application scheme or simplifying the description in the specific embodiments, and are convenient for the technicians to quickly understand the scheme, and therefore cannot be understood as indicating or implying that the specific device / component / element must have a specific orientation, or be constructed and operated in a specific position relationship, and therefore cannot be understood as limiting the application.

[0026] Furthermore, the use of terms such as "horizontal," "vertical," "suspended," "parallel," and "coaxial" does not imply that the corresponding device / component / element must be absolutely horizontal, vertical, suspended, parallel, or coaxial. Slight tilt or deviation is permissible, as long as it does not affect the normal function of the relevant component. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," not that the structure must be perfectly horizontal; a slight tilt is acceptable. "Coaxial" means that two components are arranged as coaxially as possible, allowing them to move coaxially or approximately coaxially when their relative positions change. Alternatively, it can be simplified to mean that the corresponding device / component / element, when arranged in "horizontal," "vertical," "suspended," "parallel," or "coaxial" directions, can have an error / deviation of ±10% relative to the corresponding direction, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, and more preferably within ±4%. For example, the deviation in the "coaxial" direction is controlled within 0.2-1mm, preferably within 0.2-0.5mm. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its function in the solution of the present invention.

[0027] Furthermore, the use of terms such as "first," "second," and "third" in terminology is merely for distinguishing descriptions of identical or similar components and should not be interpreted as emphasizing or implying the relative importance of a particular component.

[0028] Furthermore, in the description of the embodiments of the present invention, "several", "more than", and "a number of" represent at least two. The number can be any number, such as two, three, four, five, six, seven, eight, or nine, and can even exceed nine.

[0029] Furthermore, in the description of the technical solution of this invention, unless otherwise explicitly specified / limited / restricted, the terms "set up," "install," "connect," "link," "provided with," "laid out," and "arranged" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to connection methods commonly used in the art, such as welding, riveting, bolting, and threaded connections. Such connections can be mechanical, electrical, or communication connections; they can be direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components.

[0030] Example 1 like Figures 1-5 As shown, the small-section coal uncovering process of the tunnel arch with a small-angle roof includes the following steps: S1. Excavate a stepped drilling site. The stepped drilling site includes several steps set along the bedding plane 4 of the coal seam at an angle of dip. The top surface of each step is set as the operating platform 1, and the vertical surface is set as the drilling surface 2.

[0031] In an optional embodiment, the drilling faces 2 of adjacent steps have the same height, the inclination of the stepped drilling field is parallel to the direction of the connecting line of the edges of the steps, the inclination of the stepped drilling field deviates from the inclination of the coal seam bedding plane 4 by no more than ±5°, the stepped drilling field is designed according to the inclination of the coal seam, the inclination of the stepped drilling field is substantially the same as the inclination of the bedding plane, when the drilling is performed, the lengths of the drilling channels on each step are substantially the same, the drilling channels are substantially parallel to each other and have substantially the same drilling depth, and the axis of the drilling channel intersects the coal seam bedding plane 4 at a small angle of 10-30°.

[0032] In an optional embodiment, the number of the stepped drilling fields is more than one. One or two stepped drilling fields can be set according to the actual situation, the heights of the steps in each stepped drilling field are the same, the drilling depths are similar, the drilling and drainage holes 3 in each stepped drilling field can be efficiently and high-quality drilled, the construction efficiency is improved, and a plurality of stepped drilling fields can be set according to the actual situation, the areas of the stepped drilling fields are relatively reduced, and small cross-section coal uncovering is achieved.

[0033] S2, drilling and drainage holes 3 are drilled, a drilling machine station operating platform 1 is used, a plurality of drainage holes 3 are drilled on the drilling face 2, the drainage holes 3 are perpendicular to the drilling face 2, the axes of the transversely or longitudinally adjacent drainage holes 3 are parallel, and the drainage holes 3 form an equidistant array on the target coal seam.

[0034] In an optional embodiment, the heights of the drainage holes 3 on the drilling face 2 are 1-2 m, the hole spacing is uniform, and the drilling channels are parallel to each other and have the same depth. By uniformly distributing the drainage holes 3, the entire small-angle intersecting bedding plane area can be fully covered, the mining efficiency is improved, by making the drilling channels parallel to each other and having similar depths, a plurality of drilling holes can be uniformly distributed on the same plane of the bedding plane, the gas in the plane can be effectively drained, and because the drilling holes are parallel, the construction is relatively simple, and the management and operation are also convenient.

[0035] In an optional embodiment, the drilling direction of the drainage holes 3 is inclined according to the inclination of the coal seam bedding plane 4. For example, in coal seam gas drainage, if the inclination of the bedding plane is southeast and the inclination angle is 10°-30°, the drilling hole arrangement direction can be appropriately inclined to the southeast on the basis of ensuring a small-angle intersection with the bedding plane, which can better extend along the bedding plane and enable the drilling holes to effectively contact more gas-containing bedding fissures.

[0036] In an optional embodiment, the diameter of the drainage holes 3 is 75-115 mm, the length is 20-80 m, and the drilling spacing is determined according to the actual effective drainage radius of the coal seam, preferably, the spacing of the drainage holes 3 on the target coal seam is less than or equal to 4 m, and is preferably 4*4 m.

[0037] In an optional embodiment, the drainage holes 3 are arranged within a range of 15 m along the coal seam trend direction and 10 m above and below the normal line of the excavation contour line outside the excavation contour line of the main tunnel 5, and the drainage holes 3 are constructed by using a crawler hydraulic tunnel drill.

[0038] In an optional embodiment, the drainage holes 3 with a length of not less than 60 m can be supplemented on the drilling face 2 according to actual conditions.

[0039] In an optional embodiment, the ZDY or ZY series drill can be selected, and a reasonable drilling parameter is matched, a suitable drilling method is selected according to the specific conditions of the coal seam, the drilling speed and pressure are controlled, the drilling collapse or hole blocking phenomenon caused by too fast or too slow can be effectively avoided, and the hole collapse risk can be effectively controlled.

[0040] S3, the extraction system is built, and the drainage holes 3 are connected to the gas extraction system after being sealed, and the gas extraction system is connected with a monitoring system.

[0041] In an optional embodiment, the sealing includes pumping sealing by using polyurethane or M425 cement mortar, the sealing length is greater than or equal to 5 m when the drainage holes 3 are rock holes, and the sealing length is greater than or equal to 8 m when the drainage holes 3 are coal holes.

[0042] In one or more embodiments, the gas extraction system includes an extraction station, an extraction main pipeline and extraction branch pipes 6, the extraction main pipeline is arranged overhead in the tunnel through a support frame, the extraction branch pipes 6 are connected with the drainage holes 3 and the extraction main pipeline, and the extraction branch pipes 6 are provided with valves 7.

[0043] In an optional embodiment, the extraction station can be arranged with a double water ring vacuum pump station, the extraction main pipeline can be a DN200 mm pipeline, after the drilling and sealing of the drainage holes 3, a DN50 mm mine rubber pipe can be used to connect the drainage holes 3 with a gas collection pipe in the drilling field, the connection is tightened by iron wire, the gas collection pipe is connected with the extraction branch pipes 6, and the valves 7 are arranged at the connection to control the extraction negative pressure, and the gas collection pipe is connected with the extraction main pipeline.

[0044] In an optional embodiment, the pipeline of the gas extraction system is laid from the extraction station, and the pipeline from the pump station to the tunnel portal is laid on the ground, and the pipeline in the tunnel 5 is laid in the tunnel 5, and the pipeline in the tunnel 5 can be hung and laid, and the anchor rod is hung on the roof of the roadway.

[0045] In one or more embodiments, the monitoring system is provided with a plurality of monitoring points in the tunnel and outside the tunnel, the monitoring points are provided with automatic monitoring mechanisms and / or manual detection mechanisms, the automatic monitoring mechanisms include V-cone flow meters and gas concentration sensors, the manual detection mechanisms include detection ports and gas pipeline extraction parameter detectors, and the automatic monitoring mechanisms are connected with the tunnel 5 safety monitoring system.

[0046] In an optional embodiment, the comprehensive extraction parameter detection method combining automatic monitoring and manual detection can be used in the tunnel. Two automatic monitoring points can be arranged in the tunnel, each equipped with a V-cone flowmeter, and a manual detection port is arranged, a orifice flowmeter is arranged, and a WGCB gas pipeline extraction parameter tester can be used to check the gas concentration, extraction negative pressure, pressure difference and temperature and other parameters in the pipeline. At the same time, a V-cone flowmeter automatic monitoring device can be installed on the ground outside the tunnel, which cooperates with the gas concentration sensor to perform real-time monitoring of the gas extraction parameters, and is connected with the existing tunnel 5 safety monitoring system to realize real-time monitoring and inquiry of the ground extraction system, and ensure the safety of construction.

[0047] S4, performing extraction operation.

[0048] In an optional embodiment, during the excavation process after the extraction operation, when the working face is predicted to have a prominent risk, direct gas discharge through drilling can be used to ensure the safety of excavation.

[0049] Compared with the prior art, the small-angle roof coal uncovering tunnel vault small-section coal uncovering process of the embodiment has the following advantages: (1) improving safety: because the drilling field is ladder-shaped, the drilling channel has consistent depth, which can facilitate the prediction of the distance to the bedding surface, so as to dynamically adjust the drilling speed and pressure of the drilling machine in advance, thereby improving safety. In combination with gas extraction monitoring and control, the ground and tunnel 5 extraction parameters are monitored, which can realize the monitoring and control of pump station extraction metering, equipment operation state and working condition, system parameters, underground pipeline extraction parameters, etc., thereby greatly improving the safety of engineering construction; (2) improving work efficiency: because the ladder-type drilling field is perpendicular to the drilling hole face 2 and the drilling and drainage hole 3, the drilling pipe length is consistent, which can reduce the construction engineering quantity, and the centralized station is established to establish a high negative pressure gas extraction system, which can improve the concentration and efficiency of gas extraction, ensure the continuity and stability of gas extraction, and reduce the construction difficulty and time; (3) saving time: the overall inclination of the ladder-type drilling field is consistent with the bedding surface, and the drilling hole is vertically drilled, so the angle can be quickly determined during drilling, saving time, improving the flexibility and efficiency of construction, reducing resource waste, and ensuring the economy and feasibility of the project.

[0050] Taking a tunnel construction as an example, the small-angle roof coal uncovering tunnel 5 arch top small section uncovering technology is adopted, the hole forming rate is increased to > 95%, the hole collapse rate is reduced to < 3%; the construction efficiency is increased by about 30%, the drilling time is saved by an average of 2-3 hours per hole; the gas extraction concentration is increased by 15-20%, the extraction coverage is more uniform; it is suitable for different inclination and bedding change sections; it can reduce drilling, reduce equipment, save energy, achieve the purpose of cost control, and the safety risk is significantly reduced, and the whole process can be monitored and controlled.

[0051] The small-angle roof coal uncovering tunnel arch top small section uncovering technology of the embodiment can realize uniform distribution of drilling in the target area through the drilling channels with approximately the same length, can quickly determine the drilling angle and depth, is convenient for predicting the distance to the bedding surface, can dynamically adjust the drilling speed and pressure of the drilling machine in advance, can improve the construction safety and reduce the construction engineering quantity, can improve the construction efficiency and the hole forming rate, at the same time, the drilling channel can form a small angle intersection with the bedding surface, so that the drainage hole 3 can effectively contact more gas-containing bedding joints, can improve the coverage of the bedding surface area, is beneficial to improve the mining efficiency, can enhance the adaptability to different geological conditions, especially the adaptability to high stress soft coal seam, can ensure the stability and reliability of the drilling process.

[0052] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A small-section coal uncovering process for the arch of a tunnel with a small-angle roof, characterized in that: include: S1. Excavate a stepped drilling site, the stepped drilling site including several steps set along the dip angle of the coal seam bedding plane (4), the top surface of each step is set as an operating platform (1), and the vertical surface is set as a drilling surface (2). S2. Drill drainage holes (3). Using the drilling rig station, the operating platform (1) is used to drill several drainage holes (3) on the drilling surface (2). The drainage holes (3) are perpendicular to the drilling surface (2), and the axes of the drainage holes (3) are parallel to each other in the horizontal or vertical direction. The drainage holes (3) form a drill hole array with equal spacing on the target coal seam. S3. Build an extraction system, seal several extraction holes (3) and connect them to the gas extraction system, the gas extraction system is connected to a monitoring system; S4. Conduct sampling operations.

2. The small-angle roof coal uncovering tunnel arch small-section coal uncovering process according to claim 1, characterized in that, The drilling surfaces (2) of adjacent steps are at the same height, and the extraction hole (3) is 1-2m high on the drilling surface (2).

3. The small-angle roof coal uncovering tunnel arch small-section coal uncovering process according to claim 2, characterized in that, The drilling direction of the extraction hole (3) is inclined in accordance with the bedding plane (4) of the coal seam, and the axis of the extraction hole (3) intersects the bedding plane (4) of the coal seam at an angle of 10-30°.

4. The small-angle roof coal uncovering tunnel arch small-section coal uncovering process according to claim 3, characterized in that, The diameter of the extraction hole (3) is 75-115mm and the length is 20-80m. The spacing between the extraction holes (3) on the target coal seam is less than or equal to 4m.

5. The small-angle roof coal uncovering tunnel arch small-section coal uncovering process according to claim 1, characterized in that, The dip angle of the stepped drilling site is parallel to the direction of the line connecting the edges of the steps, and the dip angle of the stepped drilling site deviates from the dip angle of the coal seam bedding plane (4) by no more than ±5°.

6. The small-angle roof coal uncovering tunnel arch small-section coal uncovering process according to claim 5, characterized in that, The drainage holes (3) are located 15m long along the coal seam direction outside the excavation outline on both sides of the main tunnel (5) and 10m above and below the normal line of the excavation outline. The drainage holes (3) are constructed using a crawler-type hydraulic tunnel drilling rig.

7. The small-angle roof coal uncovering tunnel arch small-section coal uncovering process according to claim 5, characterized in that, The number of stepped drilling sites is one or more.

8. The small-angle roof coal uncovering tunnel arch small-section coal uncovering technology according to any one of claims 1-7, characterized in that, In S3, the sealing of the hole includes sealing the hole by pumping polyurethane or M425 cement mortar. When the drainage hole (3) is a rock hole, the sealing length is ≥5m. When the drainage hole (3) is a coal hole, the sealing length is ≥8m.

9. The small-angle roof coal uncovering tunnel arch small-section coal uncovering process according to claim 8, characterized in that, The gas extraction system includes an extraction station, a main extraction pipeline and extraction branch pipes (6). The main extraction pipeline is suspended in the tunnel by a support frame. The extraction branch pipes (6) connect the extraction hole (3) and the main extraction pipeline. Valves (7) are installed on the extraction branch pipes (6).

10. The small-angle roof coal uncovering tunnel arch small-section coal uncovering process according to claim 8, characterized in that, The monitoring system sets up several monitoring points inside and outside the tunnel. The monitoring points are equipped with automatic monitoring mechanisms and / or manual detection mechanisms. The automatic monitoring mechanism includes a V-cone flow meter and a gas concentration sensor. The manual detection mechanism includes a detection port and a gas pipeline drainage parameter measuring instrument. The automatic monitoring mechanism is connected to the tunnel (5) safety monitoring system.

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