Gas tunnel water-gas separation system and construction method

Abstract

The invention relates to the technical field of gas tunnel construction, in particular to a gas tunnel water-gas separation system and a construction method.The gas tunnel water-gas separation system is characterized in that a longitudinal blind pipe is located on the side wall of a gas tunnel and longitudinally arranged in a full-length mode; the water-gas separator comprises a first gas guide pipe located on the upper portion and a water-gas mixing box located on the lower portion, the longitudinal blind pipe is located between the first gas guide pipe and the water-gas mixing box, the first gas guide pipe is communicated with the longitudinal blind pipe, and the longitudinal blind pipe is communicated with the top of the water-gas mixing box; a second gas guide pipe is further arranged at the top of the water-gas mixing box and extends upwards to be communicated with the first gas guide pipe, and a water drainage pipe is arranged at the bottom of the water-gas mixing box and is arranged upwards in an inclined mode. The first gas guide pipe is communicated with the longitudinal blind pipe and used for discharging part of gas in the longitudinal blind pipe, and after a water-gas mixture enters the water-gas mixing box through the longitudinal blind pipe, residual gas is discharged to the first gas guide pipe through the second gas guide pipe located at the top of the water-gas mixing box and then discharged through the first gas guide pipe.

Description

Technical Field

[0001] This invention relates to the field of gas tunnel construction technology, and in particular to a gas tunnel water-gas separation system and construction method. Background Technology

[0002] Gas tunnels are formed because tunnel engineering requires passing through gas-bearing strata such as coal seams, carbonaceous shale, and oil and gas-rich rock layers. During tunnel excavation, the stress in the strata is released and the fissures in the surrounding rock are gradually connected. The gas (mainly methane) accumulated in the strata will continuously gush into the tunnel space. When the amount or concentration of gas gush reaches the industry standard limit, a gas tunnel will be formed.

[0003] During the construction of gas tunnels, groundwater and methane gas seep out simultaneously from fissures in the surrounding rock, mixing to form a gas-water mixture. If this mixture cannot be effectively separated and discharged, it will pose a serious safety hazard. When the methane concentration inside the tunnel is within the explosive limit range of 5%-16%, it is highly susceptible to violent explosions upon contact with open flames, electric sparks, or other ignition sources, causing damage to the support structure and casualties. High concentrations of methane gas will displace oxygen in the air, leading to oxygen deficiency and suffocation among construction workers. If the methane gas is mixed with toxic gases such as carbon monoxide, it can also cause poisoning.

[0004] However, the existing drainage systems of gas tunnels mostly follow the drainage structure of ordinary tunnels, often setting up a single blind pipe to directly introduce the gas-water mixture into the side ditch for discharge. When gas and water mix and flow, the gas is easily dissolved in the water or forms bubbles that remain in the drainage pipe and cannot be quickly discharged from the tunnel, resulting in excessive gas concentration in the tunnel and causing the risk of explosion and poisoning. Summary of the Invention

[0005] The purpose of this invention is to provide a gas tunnel water-gas separation system and construction method to address the problems in the background art.

[0006] In a first aspect, the present invention provides a gas tunnel water-gas separation system, comprising: Longitudinal blind pipes are located on the sidewalls of the gas tunnel and are arranged longitudinally along its length. A water-gas separator, comprising a first air guide pipe at the top and a water-gas mixing chamber at the bottom, a longitudinal blind pipe located between the first air guide pipe and the water-gas mixing chamber, the first air guide pipe being connected to the longitudinal blind pipe and the longitudinal blind pipe being connected to the top of the water-gas mixing chamber, the first air guide pipe being used to discharge methane gas; The top of the water-air mixing box is also provided with a second air guide pipe, which extends upward and connects to the first air guide pipe. The bottom of the water-air mixing box is connected to a drain pipe, which is laid out at an upward angle.

[0007] A water-gas mixture is collected from the surrounding rock of the gas tunnel via a longitudinal blind pipe. This mixture is then gathered and discharged into a water-gas separator. Since the first vent pipe is connected to the longitudinal blind pipe, it is used to discharge some of the gas inside the longitudinal blind pipe, preventing excessive gas accumulation. Furthermore, after the water-gas mixture enters the water-gas mixing box through the longitudinal blind pipe, it is separated. The separated gas is discharged to the first vent pipe through the second vent pipe located at the top of the water-gas mixing box, and then discharged through the first vent pipe. Gas is discharged directionally through the dual vent pipes, while water is discharged through the drain pipe, effectively preventing accumulation in the tunnel and ensuring tunnel construction safety. Furthermore, a drain pipe is installed at the bottom of the water-gas mixing box. The drain pipe is inclined upwards, creating a water layer at a certain height at the bottom of the water-gas mixing box, forming a water seal and preventing gas from being discharged through the drain pipe.

[0008] Preferably, the top elevation of the water-air mixing box is lower than the elevation of the longitudinal blind pipe.

[0009] Preferably, it further includes a connecting pipe, one end of which is connected to the longitudinal blind pipe, and the other end of which is bent downward and connected to the top of the water-air mixing tank.

[0010] Preferably, a mesh is installed in the middle of the water-air mixing box, and the mesh is set horizontally.

[0011] Preferably, the second air duct is equipped with a one-way valve.

[0012] Preferably, the outlet port of the drain pipe is higher than the bottom of the water-air mixing tank.

[0013] Preferably, it also includes an annular blind pipe, which is laid out circumferentially along the contour of the gas tunnel and is connected to the longitudinal blind pipe.

[0014] It also includes a gas discharge pipe, which is located at the top of the gas tunnel and is arranged longitudinally, and the first gas duct is connected to the gas discharge pipe.

[0015] In a second aspect, the present invention provides a gas-water separation system for constructing a gas tunnel, comprising the following steps: S1: Determine the gas protection section of the gas tunnel according to the design requirements, and then carry out the initial support construction; S2: The longitudinal blind pipe is laid along the longitudinal length on the side wall of the initial support, the annular blind pipe is laid along the circumference of the initial support outline at the designed interval, and the gas discharge pipe is laid along the longitudinal length at the arch position of the initial support, and the longitudinal blind pipe is connected to the annular blind pipe. S3: Install water-air separators according to the design spacing, so that the longitudinal blind pipe is located between the first air guide pipe and the water-air mixing box, and then connect the longitudinal blind pipe to the first air guide pipe and the longitudinal blind pipe to the top of the water-air mixing box respectively. One end of the second air guide pipe is connected to the top of the water-air mixing box, and the other end extends upward and is sealed and connected to the first air guide pipe. The drain pipe is installed at the bottom of the water-air mixing box, with the drain pipe laid at an upward inclination and the outlet of the drain pipe connected to the tunnel side ditch. S4: Perform a sealing test on the longitudinal blind pipe, the water-gas separator, the gas discharge pipe, and the annular blind pipe; S5: Carry out secondary lining construction.

[0016] Preferably, in S5, it further includes: After the sealing test is passed, the tunnel gas isolation layer and remaining waterproofing facilities are laid.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: The gas tunnel water-gas separation system of the present invention collects water-gas mixtures in the surrounding rock of the gas tunnel through a longitudinal blind pipe, and then collects and discharges the water-gas mixture into a water-gas separator through the longitudinal blind pipe. Since the first air guide pipe is connected to the longitudinal blind pipe, it is used to discharge part of the gas in the longitudinal blind pipe to avoid excessive accumulation of gas inside the longitudinal blind pipe. Furthermore, after the water-gas mixture enters the water-gas mixing box through the longitudinal blind pipe, it is separated. The separated gas is discharged to the first air guide pipe through the second air guide pipe located at the top of the water-gas mixing box, and then discharged through the first air guide pipe. Gas is discharged directionally through the dual air guide pipes, and water is discharged through the drain pipe, effectively avoiding accumulation in the tunnel and ensuring tunnel construction safety. Furthermore, a drain pipe is provided at the bottom of the water-gas mixing box. The drain pipe is inclined upward to create a water layer of a certain height at the bottom of the water-gas mixing box, forming a water seal to prevent gas from being discharged from the drain pipe. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the gas tunnel water-gas separation system of the present invention.

[0019] Figure 2 This is a schematic diagram showing the connection between the water-air separation system and the tunnel side ditch.

[0020] Figure 3 This is a schematic diagram of the blind pipe layout.

[0021] Marked in the image: 1-Longitudinal blind tube, 2-Water-air separator, 21-First air guide pipe, 22-Water-air mixing box, 23-Second air guide pipe, 24-Drain pipe, 25-Connecting pipe, 26-Wire mesh, 3-Gas discharge pipe, 4-Ring blind tube, 5- One-way valve. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0023] Unless otherwise specified, the use of terms such as "upper," "lower," "left," "right," "center," "inner," and "outer" to indicate orientation or positional relationships in the description of specific embodiments of the present invention is based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationship in which the product / equipment / device is typically placed during use. These terms are merely for the purpose of facilitating the description of the present invention or simplifying the description in specific embodiments, enabling those skilled in the art to quickly understand the solution, and do not indicate or imply that a particular device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship. Therefore, they should not be construed as limitations on the present invention.

[0024] 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 set 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 set in a "horizontal," "vertical," "suspended," "parallel," or "coaxial" direction, 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.

[0025] 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.

[0026] 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 2, 3, 4, 5, 6, 7, 8, or 9, and can even exceed nine.

[0027] 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 common connection methods 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.

[0028] Example 1 like Figure 1 , Figure 2 , Figure 3 As shown, this embodiment discloses a gas tunnel water-gas separation system, including: Longitudinal blind pipe 1 is located on the side wall of the gas tunnel and is arranged longitudinally along its entire length; Water-gas separator 2 includes a first air guide pipe 21 located at the top and a water-gas mixing box 22 located at the bottom. A longitudinal blind pipe 1 is located between the first air guide pipe 21 and the water-gas mixing box 22. The first air guide pipe 21 is connected to the longitudinal blind pipe 1 and the longitudinal blind pipe 1 is connected to the top of the water-gas mixing box 22. The first air guide pipe 21 is used to discharge gas. The top of the water-air mixing box 22 is also provided with a second air guide pipe 23, which extends upward and connects to the first air guide pipe 21. The bottom of the water-air mixing box 22 is connected to a drain pipe 24, which is laid out at an angle upward.

[0029] The gas tunnel water-gas separation system in this embodiment, such as Figure 1As shown, a water-gas mixture in the surrounding rock of the gas tunnel is collected through a longitudinal blind pipe 1. The water-gas mixture is then collected and discharged into a water-gas separator 2 through the longitudinal blind pipe 1. Since the first vent pipe 21 is connected to the longitudinal blind pipe 1, it is used to discharge some of the gas inside the longitudinal blind pipe 1, preventing excessive accumulation of gas inside the longitudinal blind pipe 1. Furthermore, after the water-gas mixture enters the water-gas mixing box 22 through the longitudinal blind pipe 1, it is separated. The separated gas is discharged to the first vent pipe 21 through the second vent pipe 23 located at the top of the water-gas mixing box 22, and then discharged through the first vent pipe 21. Gas is discharged directionally through the dual vent pipes, and water is discharged through the drain pipe, effectively preventing accumulation in the tunnel and ensuring tunnel construction safety. Furthermore, a drain pipe 24 is provided at the bottom of the water-gas mixing box 22. The drain pipe 24 is inclined upward, so that there is a certain height of water layer at the bottom of the water-gas mixing box 22, forming a water seal and preventing gas from being discharged from the drain pipe 24.

[0030] In optional implementations, such as Figure 1 As shown, the top elevation of the water-air mixing box 22 is lower than the elevation of the longitudinal blind pipe 1.

[0031] A height difference is created between the water-air mixing chamber 22 and the longitudinal blind pipe 1. This height difference guides the air-water mixture to flow smoothly into the water-air mixing chamber 22, preventing the air-water mixture from stagnating in the longitudinal blind pipe 1 and effectively improving the flow capacity of the longitudinal blind pipe 1.

[0032] In optional implementations, such as Figure 1 As shown, it also includes a connecting pipe 25, one end of which is connected to the longitudinal blind pipe 1, and the other end of which bends downward and connects to the top of the water-air mixing box 22. The downwardly bent connecting pipe 25 optimizes the flow path and facilitates the guidance of the air-water mixture to flow into the water-air mixing box 22.

[0033] In optional implementations, such as Figure 1 As shown, a mesh 26 is installed in the middle of the water-gas mixing chamber 22, and the mesh 26 is set horizontally. The mesh 26 can effectively promote gas-water separation. After the gas-water mixture comes into contact with the mesh 26, tiny water droplets adhere to and gather on the mesh 26 to form large water droplets, which settle under the action of gravity. The gas passes through the mesh and floats to the top, collecting at the top of the water-gas mixing chamber 22, and then is discharged into the first gas guide pipe 21 through the second gas guide pipe 23, which greatly improves the separation efficiency.

[0034] In optional implementations, such as Figure 1 As shown, a one-way valve 5 is installed on the second gas duct 23. By installing the one-way valve 5 on the second gas duct 23, gas backflow or air backflow is prevented, ensuring that the gas emission path is unidirectionally controllable; further reducing the risk of leakage and explosion.

[0035] In an optional implementation, a gas alarm device is installed on the drain pipe 24. This device monitors gas leaks in the drain pipe in real time and issues timely warnings; it also facilitates rapid handling of leaks during construction and maintenance, reducing safety risks.

[0036] In optional implementations, such as Figure 1 , Figure 3 As shown, it also includes an annular blind pipe 4, which is laid out circumferentially along the outline of the gas tunnel and is connected to the longitudinal blind pipe 1. The annular blind pipe 4 is used to further collect water and gas mixtures in the surrounding rock of the gas tunnel, expanding the collection range.

[0037] In optional implementations, such as Figure 1 As shown, it also includes a gas discharge pipe 3, which is located on the roof of the gas tunnel and is arranged longitudinally. The first gas duct 21 is connected to the gas discharge pipe 3.

[0038] To achieve centralized and directional gas emission and prevent it from spreading into the tunnel, the gas emission pipe 3 is led out of the gas tunnel and emitted at a high position. The first gas guide pipe 21 is connected to the gas emission pipe 3 through a pipe of the same type and material.

[0039] In an optional embodiment, the drain pipe 24 is connected to the bottom of the water-gas mixing box 22. The drain pipe 24 is inclined upward, and the water outlet of the drain pipe 24 is higher than the bottom of the water-gas mixing box 22. Specifically, the water outlet of the drain pipe 24 extends inclined upward to near the middle of the water-gas mixing box 22, so that there is a certain height of water layer at the bottom of the water-gas mixing box 22, forming a water seal to prevent gas from being discharged from the drain pipe 24. For example, if the height of the water-gas mixing box 22 is 1 meter, the height of the water outlet of the drain pipe 24 is about 0.4-0.6 meters. After construction, water is first injected into the water-gas mixing box 22 until the water layer has a certain height, submerging the water inlet of the drain pipe 24 at the bottom of the water-gas mixing box 22, so as to form a water seal at the bottom of the water-gas mixing box 22 in advance.

[0040] Furthermore, the outlet port of the drain pipe 24 is connected to the tunnel side ditch. Specifically, a connecting pipe is installed at the outlet port of the drain pipe 24, and this pipe is connected to the tunnel side ditch, such as... Figure 2 .

[0041] In an optional embodiment, the water-air mixing box 22 is a reinforced concrete box structure.

[0042] In an optional implementation, the gas isolation layer uses an EVA waterproof membrane and a geotextile cushion layer. The EVA waterproof membrane has a thickness of not less than 1.5 mm and a width of not less than 3 meters. The geotextile cushion layer uses geotextile with a unit area mass of not less than 400 g / m2 and a nominal tensile strength of not less than 20 KN / m.

[0043] In an optional embodiment, the longitudinal blind tube 1 and the annular blind tube 4 are selected as porous polyethylene blind tubes.

[0044] In an optional embodiment, the drain pipe 24 may be a PE pipe, a PVC pipe, or a steel-reinforced polyethylene plastic composite pipe.

[0045] In an optional embodiment, the first air guide tube 21 and the second air guide tube 23 are selected as steel-reinforced polyethylene plastic composite tubes.

[0046] In an optional implementation, the gas discharge pipe 3 is selected as a steel-reinforced polyethylene plastic composite pipe.

[0047] In an optional implementation, the gas alarm device uses an SGA-500 pipeline flange-type methane detector. Example 2 Based on Example 1, this example discloses a construction method for a gas tunnel water vapor separation system, used for constructing the gas tunnel water vapor separation system described in Example 1, including the following steps: S1: Determine the gas protection section of the gas tunnel according to the design requirements, and then carry out the initial support construction; Among them, the initial support deformation monitoring equipment is deployed. After the initial support construction is completed, continuous monitoring of surrounding rock settlement and convergence deformation is started. After the initial support deformation is determined to be stable, the pipeline is installed.

[0048] S2: Install longitudinal blind pipe 1 along the longitudinal length on the side wall of the initial support, install annular blind pipe 4 along the circumference of the initial support outline at the designed spacing, install gas discharge pipe 3 along the longitudinal length at the arch position of the initial support, and connect longitudinal blind pipe 1 and annular blind pipe 4. Among them, the ring-shaped blind pipe 4 is laid out circumferentially along the initial support outline, with a spacing of 10 meters. Longitudinal blind pipe 1 is laid along the longitudinal length of the tunnel sidewall to ensure that the pipe is smooth and without bends. During installation, the elevation of longitudinal blind pipe 1 is controlled to ensure that the top elevation of the subsequent water-air mixing box 22 is lower than the elevation of longitudinal blind pipe 1. The annular blind pipe 4 is connected to longitudinal blind pipe 1 through a tee joint.

[0049] S3: Install water-air separators 2 according to the designed spacing, with one water-air separator 2 every 10 meters; Position the longitudinal blind tube 1 between the first air guide tube 21 and the water-air mixing box 22, and then connect the longitudinal blind tube 1 to the first air guide tube 21 and the longitudinal blind tube 1 to the top of the water-air mixing box 22 respectively. The longitudinal blind pipe 1 is connected to the water-air mixing box 22 by a connecting pipe 25. One end of the connecting pipe 25 is sealed to the longitudinal blind pipe 1, and the other end is bent downwards and sealed to the top of the water-air mixing box 22. One end of the second air pipe 23 is connected to the top of the water-air mixing box 22, and the other end extends upward and is sealed and connected to the first air pipe 21. Among them, the one-way valve 5 is installed in the middle of the second gas pipe 23 to prevent the gas from flowing back into the first gas pipe 21; A drain pipe 24 is installed at the bottom of the water-air mixing box 22, with the drain pipe 24 laid at an upward angle and the outlet of the drain pipe 24 connected to the tunnel side ditch. Drainage pipe 24 is laid in an upward inclined manner, and its outlet is connected to the tunnel side ditch; Among them, a gas alarm device is installed at the port of the drain pipe to monitor the gas leakage in the drain pipe in real time and issue an early warning in a timely manner; this facilitates the rapid handling of leakage problems during construction and operation and maintenance, and reduces safety risks.

[0050] Furthermore, a mesh 26 is horizontally installed in the middle of the water-air mixing box 22 to ensure that the mesh 26 is firmly fixed, flat and free from deformation; S4: Conduct a sealing test on the longitudinal blind pipe 1, water-gas separator 2, gas discharge pipe 3, and annular blind pipe 4; Including but not limited to the following tests: (1) Air tightness test: Test pressure 0.3MPa, pressure held for 30min with no leakage; (2) Flow test: water flow capacity ≥ 0.5 m³ / h, and aeration capacity meets the gas emission requirements; (3) Functional test: Verify the effectiveness of the one-way valve in preventing backflow and the response sensitivity of the gas alarm device.

[0051] S5: Carry out secondary lining construction.

[0052] In an optional implementation, S5 further includes: After the sealing test is passed, the tunnel gas isolation layer and remaining waterproofing facilities are laid. This ensures the sealing effect of the gas isolation layer and effectively blocks the gas seepage path.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A gas tunnel water-gas separation system, characterized in that, include: Longitudinal blind pipe (1) is located on the side wall of the gas tunnel and is arranged longitudinally along its length; A water-gas separator (2) includes a first air guide pipe (21) located at the top and a water-gas mixing box (22) located at the bottom. A longitudinal blind pipe (1) is located between the first air guide pipe (21) and the water-gas mixing box (22). The first air guide pipe (21) is connected to the longitudinal blind pipe (1), and the longitudinal blind pipe (1) is connected to the top of the water-gas mixing box (22). The first air guide pipe (21) is used to discharge gas. The top of the water-air mixing box (22) is also provided with a second air guide pipe (23), which extends upward and connects to the first air guide pipe (21). The bottom of the water-air mixing box (22) is connected to a drain pipe (24), which is inclined upward.

2. The gas tunnel water-gas separation system according to claim 1, characterized in that, The top elevation of the water-air mixing box (22) is lower than the elevation of the longitudinal blind pipe (1).

3. The gas tunnel water-gas separation system according to claim 1, characterized in that, It also includes a connecting pipe (25), one end of which is connected to the longitudinal blind pipe (1), and the other end of which is bent downward and connected to the top of the water-air mixing box (22).

4. A gas tunnel water-gas separation system according to claim 1, characterized in that, A mesh (26) is installed in the middle of the water-air mixing box (22), and the mesh (26) is set horizontally.

5. A gas tunnel water-gas separation system according to claim 1, characterized in that, The second air duct (23) is equipped with a one-way valve (5).

6. A gas tunnel water-gas separation system according to claim 1, characterized in that, The outlet of the drain pipe (24) is higher than the bottom of the water-air mixing box (22).

7. A gas tunnel water-gas separation system according to claim 1, characterized in that, It also includes an annular blind pipe (4), which is laid out circumferentially along the outline of the gas tunnel, and the annular blind pipe (4) is connected to the longitudinal blind pipe (1).

8. A gas tunnel water-gas separation system according to claim 1, characterized in that, It also includes a gas discharge pipe (3), which is located at the top of the gas tunnel and is arranged longitudinally. The first gas duct (21) is connected to the gas discharge pipe (3).

9. A construction method for a water-gas separation system in a gas tunnel, characterized in that, The method for constructing a gas tunnel water-gas separation system as described in any one of claims 1-8 includes the following steps: S1: Determine the gas protection section of the gas tunnel according to the design requirements, and then carry out the initial support construction; S2: The longitudinal blind pipe (1) is laid out along the longitudinal length on the side wall of the initial support, the annular blind pipe (4) is laid out along the circumference of the initial support outline at the designed spacing, the gas discharge pipe (3) is laid out along the longitudinal length at the arch position of the initial support, and the longitudinal blind pipe (1) is connected to the annular blind pipe (4). S3: Arrange the water-air separators (2) according to the design spacing, so that the longitudinal blind pipe (1) is located between the first air guide pipe (21) and the water-air mixing box (22), and then connect the longitudinal blind pipe (1) to the first air guide pipe (21) and the top of the water-air mixing box (22) respectively. One end of the second air guide pipe (23) is connected to the top of the water-air mixing box (22), and the other end extends upward and is sealed and connected to the first air guide pipe (21); The drain pipe (24) is installed at the bottom of the water-air mixing box (22), and the drain pipe (24) is laid out at an angle upward, and the outlet of the drain pipe (24) is connected to the tunnel side ditch; S4: Perform a sealing test on the longitudinal blind pipe (1), the water-gas separator (2), the gas discharge pipe (3), and the annular blind pipe (4); S5: Carry out secondary lining construction.

10. A construction method for a gas tunnel water-gas separation system according to claim 9, characterized in that, S5 also includes: After the sealing test is passed, the tunnel gas isolation layer and remaining waterproofing facilities are laid.

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