An ultra-long distance high-gas tunnel earth pressure balance shield gas pumping system

Abstract

The application relates to an ultra-long-distance high-gas tunnel earth pressure balance shield gas pumping system, which comprises an earth pressure balance shield including a shield soil bin located at the back of a cutter head, the shield soil bin being connected with an air inlet pipe for feeding compressed gas into the shield soil bin; a muck conveying mechanism including a screw conveyor connected with the shield soil bin and a belt conveyor closed section connected with a muck outlet of the screw conveyor for conveying muck; and a gas pumping pipeline including a gas pumping branch pipe in communication with the shield soil bin and the belt conveyor closed section and a gas pumping main pipe connected with the gas pumping branch pipe. The application pumps the compressed gas into the shield soil bin through the air inlet pipe to displace a large amount of gas accumulated in the shield soil bin. In the process of conveying the muck by the screw conveyor and the belt conveyor closed section, the gas is fully stirred and released, and the release time of the gas in the muck is prolonged, so that the gas concentration after entering an open area can be controlled within a safe range.

Description

Technical Field

[0001] This application relates to the field of tunnel boring machine technology, and in particular to a gas extraction system for earth pressure balance tunnel boring machines used in ultra-long-distance high-gas tunnels. Background Technology

[0002] Tunnel boring machines are widely used in infrastructure construction such as railways, highways, rail transit, and integrated utility tunnels.

[0003] With the increasing demand for tunnel construction in complex geological formations, uncertainties still exist that constrain the safety of tunnel boring machines (TBMs). Taking tunnels in gas-rich formations as an example, during earth pressure balance TBM tunneling, gas can easily seep and diffuse through the muck removal system, causing accidents such as personnel asphyxiation and gas explosions. Given the primary weakness of the TBM muck removal system—its susceptibility to gas accumulation and leakage—it is essential to design a drainage system to reduce the gas concentration within the TBM's muck chamber, screw conveyor, and belt conveyor.

[0004] Literature review indicates that preliminary research has been conducted on gas drainage systems for earth pressure balance shield tunneling machines. For example, Chinese invention patent application publication number CN108386199A proposes a safe and efficient shield tunneling method and device for high-gas outburst coal seams. This method prevents gas emissions from the excavation face from exceeding gas limits in the roadway by connecting the gas drainage pipe to the gas-water-slag chamber, the air extraction hole of the longitudinal isolation cavity, and the air outlet of the gas discharge coal outlet. However, this device does not include gas drainage design for the shield tunneling slag removal system, and therefore cannot prevent combustion and explosion accidents caused by the release of gas during the slag removal process.

[0005] For example, Chinese invention patent application publication number CN112746851A proposes a gas control system for tunnel boring machines (TBMs). This system uses an air intake pipe connected to the soil chamber as a gas extraction channel for the TBM's soil chamber. This gas extraction design can only meet the needs of tunneling with low-concentration methane. However, during the excavation of high-methane tunnels, the methane in the TBM's soil chamber is difficult to completely release, and the methane gas released after the excavated soil enters the screw conveyor will still leak into the tunnel interior.

[0006] For example, Chinese invention patent application publication number CN109026153A proposes a gas prevention and control device for earth pressure balance shield tunneling. This device involves fixing a high-sensitivity gas sensor above the slag discharge port of the screw conveyor to detect the gas concentration in the vicinity and transmitting the data to a control system that controls the screw conveyor gate. When the gas concentration reaches 0.05%, the control system automatically closes the screw conveyor gate. While this method can prevent gas from entering the tunnel from the screw conveyor, it also blocks the slag discharge channel, causing a temporary shutdown of the earth pressure balance shield tunneling machine.

[0007] In summary, existing gas drainage schemes do not fully consider the leakage channels of the slag removal system. Gas can enter the tunnel through the shield tunneling chamber, spiral conveyor, and belt conveyor, making it difficult to meet the safe excavation requirements of ultra-long-distance high-gas tunnels. Summary of the Invention

[0008] This application provides a gas extraction system for earth pressure balance shield tunneling of ultra-long-distance high-gas tunnels to solve the problem of gas leakage and diffusion into the tunnel through the slag removal system during the excavation of ultra-long-distance high-gas tunnels using earth pressure balance shield tunneling, which can cause combustion and explosion accidents.

[0009] This application provides a gas extraction system for an earth pressure balance shield tunneling machine used for ultra-long-distance high-gas tunnels, comprising:

[0010] Earth pressure balance shield tunneling machine, the earth pressure balance shield tunneling machine includes a shield soil chamber located on the back of the cutterhead, the shield soil chamber is connected to an air inlet pipe for introducing compressed gas into the shield soil chamber;

[0011] The slag conveying mechanism includes a screw conveyor connected to the shield tunnel soil chamber, and a closed section of a belt conveyor connected to the slag outlet of the screw conveyor for conveying slag.

[0012] The gas extraction pipeline includes a gas extraction branch pipe connected to the shield tunnel soil chamber and the closed section of the belt conveyor, and a gas extraction main pipe connected to the gas extraction branch pipe.

[0013] In some embodiments: the closed section of the belt conveyor includes a belt conveyor and a closed pipe shell covering the outer periphery of the belt conveyor. The closed pipe shell extends along the length direction of the belt conveyor and is sealed to the slag outlet of the screw conveyor. The closed pipe shell is connected to the gas extraction branch pipe to extract gas from the closed pipe shell.

[0014] In some embodiments: a gas concentration sensor for monitoring the gas concentration inside the sealed tube is provided at the end of the sealed tube shell. The sealed tube shell is composed of several tube shell segments that are sequentially extended and sealed to each other. The length of each tube shell segment is 300-500 mm.

[0015] In some embodiments: the air inlet pipe is connected to an air compressor that supplies compressed gas into the shield soil chamber, the shield soil chamber is equipped with a pressure sensor that monitors the gas pressure inside the shield soil chamber, and the air inlet pipe is connected to an electrically controlled regulating valve that controls the gas pressure inside the shield soil chamber.

[0016] In some embodiments: a gas concentration sensor is provided in the shield soil chamber to monitor the gas concentration in the shield soil chamber, and the electronically controlled regulating valve adjusts the flow rate of compressed air introduced into the shield soil chamber according to the gas concentration in the shield soil chamber.

[0017] In some embodiments, the end of the screw conveyor is provided with a gas extraction branch pipe connected to the main gas extraction pipe. This gas extraction branch pipe is located near the slag outlet of the screw conveyor, away from the shield soil chamber, to minimize the disturbance of gas extraction to the pressure in the shield soil chamber. Valves are provided at the connections of the gas extraction branch pipe to the shield soil chamber, the gas extraction branch pipe to the screw conveyor, and the gas extraction branch pipe to the closed section of the belt conveyor to open or close the gas extraction branch pipe.

[0018] In some embodiments: the excavation chamber of the earth pressure balance shield is equipped with a pneumatic fan and a ventilation duct for supplying fresh air into the excavation chamber. The ventilation duct is equipped with a ventilation fan in each section. The excavation chamber of the earth pressure balance shield is equipped with a gas concentration sensor for monitoring gas concentration. When the gas concentration in the excavation chamber is greater than a set threshold, the pneumatic fan should be activated and the output power of the ventilation fan should be increased.

[0019] In some embodiments, the gas extraction main pipe is equipped with multiple extraction pumps that discharge gas to the ground.

[0020] In some embodiments: the outlet end of the closed section of the belt conveyor is provided with an open section of the belt conveyor for transferring slag, and the outlet end of the closed section of the belt conveyor is located above the open section of the belt conveyor.

[0021] In some embodiments, the gas extraction branch pipe is connected to the gas extraction main pipe via a corrugated pipe or flexible hose with adjustable length.

[0022] The beneficial effects of the technical solution provided in this application include:

[0023] This application provides a gas extraction system for an ultra-long-distance high-gas tunnel earth pressure balance shield. The system incorporates an earth pressure balance shield, which includes a shield chamber located on the back of the cutterhead. The shield chamber is connected to an air inlet pipe for introducing compressed gas into the chamber. A slag conveying mechanism includes a screw conveyor connected to the shield chamber and a closed section of a belt conveyor connected to the screw conveyor's outlet for transporting slag. A gas extraction pipeline includes branch pipes connected to the shield chamber and the closed section of the belt conveyor, and a main gas extraction pipe connected to the branch pipes.

[0024] Therefore, the ultra-long-distance high-gas tunnel earth pressure balance shield gas extraction system of this application first pumps compressed gas into the shield soil chamber through the air inlet pipe. The compressed gas entering the shield soil chamber can displace a large amount of gas accumulated inside the shield soil chamber, and then enters the gas extraction main pipe through the gas extraction branch pipe before finally being discharged to the ground. Secondly, during the process of transporting excavated soil in the closed section of the screw conveyor and belt conveyor, gas is released by thorough mixing and the release time of gas in the excavated soil is extended. The residual gas released from the excavated soil enters the gas extraction main pipe through the gas extraction branch pipe before finally being discharged to the ground. This ensures that the gas concentration after entering the open section of the belt conveyor is controlled within a safe range, effectively mitigating the risk of explosion accidents inside the shield and tunnel. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the earth pressure balance shield tunnel gas extraction system according to an embodiment of this application;

[0027] Figure 2 This is a schematic diagram of the gas extraction structure inside the shield tunnel's earth chamber, according to an embodiment of this application.

[0028] Figure 3 This is a schematic diagram of the gas extraction structure of the slag conveying mechanism in an embodiment of this application.

[0029] Figure label:

[0030] 1. Earth pressure balance shield tunnel; 2. Shield tunnel earth chamber; 3. Screw conveyor; 4. Open section of belt conveyor; 5. Closed section of belt conveyor; 6. Air compressor; 7. Air inlet pipe; 8. Pressure sensor; 9. Exhaust pump; 10. Gas exhaust main pipe; 11. Gas exhaust branch pipe; 12. Gas concentration sensor; 13. Valve; 14. Pneumatic fan; 15. Ventilation fan; 16. Ventilation duct. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] This application provides a gas extraction system for earth pressure balance shield tunneling of ultra-long-distance high-gas tunnels, which can solve the problem of gas leakage and diffusion into the tunnel through the shield muck removal system during the excavation of ultra-long-distance high-gas tunnels, causing combustion and explosion accidents.

[0033] See Figures 1 to 3 As shown in the figure, this application provides a gas extraction system for an earth pressure balance shield tunneling machine for ultra-long-distance high-gas tunnels, comprising:

[0034] Earth pressure balance (EPB) shield tunneling machine 1 includes a shield chamber 2 located behind the cutterhead. The shield chamber 2 is connected to an air inlet pipe 7 for introducing compressed gas into it. During tunneling in gas-rich strata, the excavated soil cut by the cutterhead enters the shield chamber 2. Under the repeated agitation of the agitator within the shield chamber 2, a large amount of methane gas is released from the excavated soil. Compressed gas (such as compressed air) is then pumped into the shield chamber 2 through the air inlet pipe 7. The compressed air mixes with the methane gas to reduce its concentration and displace the accumulated methane gas inside the shield chamber 2.

[0035] The excavated soil conveying mechanism includes a screw conveyor 3 connected to the shield tunneling soil chamber 2, and a closed section 5 of a belt conveyor connected to the discharge port of the screw conveyor 3 for conveying excavated soil. The discharge port of the screw conveyor 3 extends into the shield tunneling soil chamber 2 and is sealed to it, allowing it to convey the excavated soil from the chamber 2 to the outside. During conveying, the screw conveyor 3 agitates the excavated soil, accelerating the release of any methane gas contained within it. The excavated soil discharged from the discharge port of the screw conveyor 3 enters the closed section 5 of the belt conveyor. Within the closed section 5, the methane gas continues to be fully released, and any remaining methane gas is pumped to the ground for purification after entering the gas extraction branch pipe 11.

[0036] The gas extraction pipeline includes a gas extraction branch pipe 11 connected to the shield tunneling chamber 2 and the closed section 5 of the belt conveyor, and a gas extraction main pipe 10 connected to the gas extraction branch pipe 11. The gas extraction main pipe 10 is equipped with multiple extraction pumps 9 for discharging methane gas to the surface. Methane gas released from the shield tunneling chamber 2 and from the screw conveyor 3 and the closed section 5 of the belt conveyor are collected through the gas extraction branch pipe 11. The collected methane gas is purified through the gas extraction main pipe 10 before being discharged to the surface for further purification, ensuring that the methane concentration in the open area of ​​the tunnel is controlled within a safe range.

[0037] The gas extraction system for ultra-long-distance high-gas tunnel earth pressure balance shield tunneling in this embodiment first pumps compressed gas into the shield chamber 2 through the air inlet pipe 7. The compressed gas entering the shield chamber 2 can displace a large amount of gas accumulated inside the shield chamber 2, and then enters the gas extraction main pipe 10 through the gas extraction branch pipe 11. After purification treatment, it is discharged to the ground. The gas extraction branch pipe 11 and the gas extraction main pipe 10 are connected by a corrugated pipe or flexible hose with adjustable length. The length of the corrugated pipe or flexible hose can be adaptively adjusted to facilitate continuous gas extraction during the continuous tunneling process of the earth pressure balance shield tunneling machine 1.

[0038] Secondly, during the process of transporting excavated soil using the screw conveyor 3 and the closed section 5 of the belt conveyor, the screw conveyor 3 first mixes and fully releases the methane gas, and then the closed section 5 of the belt conveyor releases the residual methane gas. During this period, the methane gas is extracted through the gas extraction branch pipe 11, so that it enters the gas extraction main pipe 10 in time, and after purification treatment, it is extracted to the ground. This ensures that the methane concentration after entering the open area of ​​the belt conveyor is controlled within a safe range, effectively mitigating the risk of explosion accidents inside the shield tunnel and tunnel.

[0039] In some alternative embodiments: see Figure 1 and Figure 3 As shown in the figure, this application embodiment provides a gas extraction system for an earth pressure balance shield tunnel of an ultra-long distance high-gas tunnel. The closed section 5 of the belt conveyor of the gas extraction system includes a belt conveyor (not shown in the figure) and a closed shell covering the outer periphery of the belt conveyor. When the belt conveyor transports excavated soil, the residual gas released by the excavated soil fills the inside of the closed shell. The closed shell extends along the length of the belt conveyor and is sealed to the slag outlet of the screw conveyor 3. The closed shell is connected to the gas extraction branch pipe 11 to extract the gas accumulated in the closed shell.

[0040] A gas concentration sensor 12 is installed at the end of the closed pipe shell to monitor the gas concentration inside. If the gas concentration sensor 12 detects that the gas concentration inside the closed pipe shell exceeds a set value, an early warning will be issued. The gas concentration inside the closed pipe shell can be reduced by extending the length of the closed pipe shell or accelerating the flow rate of gas extraction. The closed pipe shell is composed of several pipe shell segments that are sequentially extended and sealed to each other. The length of the closed pipe shell can be adjusted according to the gas concentration inside. When the gas concentration increases, the length of the closed pipe shell should be increased. The length of the pipe shell segment is 300-500mm. An open section 4 of the belt conveyor for transferring slag is installed at the outlet end of the closed section 5 of the belt conveyor. The outlet end of the closed section 5 of the belt conveyor is located above the open section 4 of the belt conveyor.

[0041] In some alternative embodiments: see Figure 1 and Figure 2As shown in the figure, this application embodiment provides a gas extraction system for an ultra-long-distance high-gas tunnel earth pressure balance shield tunnel. The gas extraction system has an air intake pipe 7 connected to an air compressor 6 that introduces compressed gas into the shield tunnel earth chamber 2. The air compressor 6 introduces compressed fresh air through the air intake pipe 7 into the shield tunnel earth chamber 2 to displace the gas inside. A pressure sensor 8 is installed inside the shield tunnel earth chamber 2 to monitor the gas pressure. An electrically controlled regulating valve is connected to the air intake pipe 7 to control the gas pressure inside the shield tunnel earth chamber 2.

[0042] A gas concentration sensor 12 is installed inside the shield tunnel's soil chamber 2 to monitor the gas concentration within the chamber. An electrically controlled regulating valve adjusts the flow rate of compressed air entering the shield tunnel's soil chamber 2 based on the gas concentration. When the monitored gas concentration in the shield tunnel's soil chamber 2 increases, the electrically controlled regulating valve should increase the flow rate of compressed air pumped into the shield tunnel's soil chamber 2 by the air compressor 6. When the monitored gas concentration in the shield tunnel's soil chamber 2 decreases, the electrically controlled regulating valve should maintain or appropriately reduce the flow rate of air pumped into the shield tunnel by the air compressor 6 to minimize the impact on the soil chamber pressure and the stability of the tunnel face.

[0043] In this embodiment, a pressure sensor 8 is installed inside the shield tunnel soil chamber 2 to monitor the gas pressure inside the chamber. An electrically controlled regulating valve is connected to the air inlet pipe 7 to control the gas pressure inside the chamber. The pressure sensor 8 can dynamically adjust the compressed air pumping volume of the air compressor 6 according to the monitoring results. The electrically controlled regulating valve installed on the air inlet pipe 7 is used to regulate the gas pressure inside the shield tunnel soil chamber 2 so as to keep the gas pressure inside the chamber balanced with the excavation face pressure, thereby reducing the impact on the pressure disturbance of the soil chamber and the stability of the tunnel face.

[0044] In some alternative embodiments: see Figure 1 and Figure 3 As shown in the figure, this application embodiment provides a gas extraction system for an ultra-long-distance high-gas tunnel earth pressure balance shield tunnel. The end of the screw conveyor 3 of this gas extraction system is provided with a gas extraction branch pipe 11 connected to the gas extraction main pipe 10. Valves 13 are provided at the connection points of the gas extraction branch pipe 11 with the shield soil chamber 2, the connection points of the gas extraction branch pipe 11 with the screw conveyor 3, and the connection points of the gas extraction branch pipe 11 with the closed section 5 of the belt conveyor to open or close the gas extraction branch pipe 11.

[0045] During the excavation of the earth pressure balance shield tunnel 1, the opening and closing of valves 13 at the connections of the gas extraction branch pipe 11 and the shield soil chamber 2, the gas extraction branch pipe 11 and the screw conveyor 3, and the gas extraction branch pipe 11 and the closed section 5 of the belt conveyor can be controlled according to the gas concentration in the stratum. When the gas concentration in the stratum is too high, valves 13 can be fully opened to extract the gas; when the gas concentration in the stratum is low, valves 13 can be partially opened to extract the gas; when there is no gas in the stratum, valves 13 can be fully closed to stop gas extraction.

[0046] In some alternative embodiments: see Figure 1 and Figure 3 As shown in the figure, this application embodiment provides a gas extraction system for an ultra-long-distance high-gas tunnel earth pressure balance shield. The earth pressure balance shield 1 of this gas extraction system is equipped with a pneumatic fan 14 and a ventilation duct 16 for introducing fresh air into the earth pressure balance shield 1. Ventilation fans 15 are installed between sections of the ventilation duct 16. A gas concentration sensor 12 for monitoring gas concentration is installed inside the earth pressure balance shield 1. When the gas concentration inside the earth pressure balance shield 1 exceeds a set threshold, the pneumatic fan 14 should be activated, and the output power of the ventilation fan 15 should be increased.

[0047] In this embodiment, a methane concentration sensor 12 is installed inside the earth pressure balance shield tunnel 1 to monitor methane concentration. The methane concentration sensor 12 can monitor the methane concentration in real time and will issue an early warning when the methane concentration exceeds 1%. On one hand, the pneumatic fan 14 will be activated to disperse the methane gas accumulated nearby. On the other hand, the power of the ventilation fan 15 and the air volume of the ventilation duct 16 will be increased to dilute the methane gas concentration inside the earth pressure balance shield tunnel 1 in a timely manner.

[0048] Working principle

[0049] This application provides a gas extraction system for an ultra-long-distance high-gas tunnel earth pressure balance shield. The system includes an earth pressure balance shield 1, which comprises a shield soil chamber 2 located on the back of the cutterhead. The shield soil chamber 2 is connected to an air inlet pipe 7 for introducing compressed gas into the shield soil chamber 2. A slag conveying mechanism includes a screw conveyor 3 connected to the shield soil chamber 2, and a closed section 5 of a belt conveyor connected to the slag outlet of the screw conveyor 3 for conveying slag. A gas extraction pipeline includes a gas extraction branch pipe 11 connected to the shield soil chamber 2 and the closed section 5 of the belt conveyor, and a main gas extraction pipe 10 connected to the gas extraction branch pipe 11.

[0050] Therefore, the ultra-long-distance high-gas tunnel earth pressure balance shield gas extraction system of this application first pumps compressed gas into the shield earth chamber 2 through the air inlet pipe 7. The compressed gas entering the shield earth chamber 2 can displace a large amount of gas accumulated inside the shield earth chamber 2. The gas enters the gas extraction main pipe 10 through the gas extraction branch pipe 11, and after purification treatment, it is finally extracted to the ground. Secondly, the screw conveyor 3 is used to fully release the gas by stirring, and the residual gas is released through the closed section 5 of the belt conveyor. During this period, gas is extracted through the gas extraction branch pipe 11, so that it enters the gas extraction main pipe 10 in a timely manner, and is finally discharged to the ground after purification treatment. This can keep the gas concentration within a safe range after entering the open section of the belt conveyor, effectively mitigating the risk of explosion accidents inside the shield and tunnel.

[0051] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0052] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0053] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A gas extraction system for earth pressure balance shield tunneling in ultra-long-distance high-gas tunnels, characterized in that, include: Earth pressure balance shield (1), the earth pressure balance shield (1) includes a shield soil chamber (2) located on the back of the cutterhead, the shield soil chamber (2) is connected to an air inlet pipe (7) for introducing compressed gas into the shield soil chamber (2); The slag conveying mechanism includes a screw conveyor (3) connected to the shield soil chamber (2) and a closed section (5) of a belt conveyor connected to the slag outlet of the screw conveyor (3) for conveying slag. The gas extraction pipeline includes a gas extraction branch pipe (11) connected to the shield soil chamber (2) and the closed section (5) of the belt conveyor, and a gas extraction main pipe (10) connected to the gas extraction branch pipe (11). The closed section (5) of the belt conveyor includes a belt conveyor and a closed pipe shell covering the outer periphery of the belt conveyor. The closed pipe shell extends along the length of the belt conveyor and is sealed to the slag outlet of the screw conveyor (3). The closed pipe shell is connected to the gas extraction branch pipe (11) to extract gas from the closed pipe shell. The air inlet pipe (7) is connected to an air compressor (6) that supplies compressed gas into the shield soil chamber (2). The shield soil chamber (2) is equipped with a pressure sensor (8) that monitors the gas pressure inside the shield soil chamber. The air inlet pipe (7) is connected to an electrically controlled regulating valve that controls the gas pressure inside the shield soil chamber (2). The shield soil chamber (2) is equipped with a gas concentration sensor (12) for monitoring the gas concentration inside the shield soil chamber (2). The electrically controlled regulating valve adjusts the flow rate of compressed air into the shield soil chamber (2) according to the gas concentration inside the shield soil chamber (2). The end of the screw conveyor (3) is provided with a gas extraction branch pipe (11) connected to the gas extraction main pipe (10). The gas extraction branch pipe (11) is provided with a valve (13) for opening or closing the gas extraction branch pipe (11) at the connection between the gas extraction branch pipe (11) and the shield soil chamber (2), the connection between the gas extraction branch pipe (11) and the screw conveyor (3), and the connection between the gas extraction branch pipe (11) and the closed section (5) of the belt conveyor. The earth pressure balance shield (1) is equipped with a pneumatic fan (14) and a ventilation duct (16) for supplying fresh air into the earth pressure balance shield (1). The ventilation duct (16) is equipped with a ventilation fan (15) between sections. The earth pressure balance shield (1) is equipped with a gas concentration sensor (12) for monitoring gas concentration. When the concentration inside the earth pressure balance shield (1) is greater than a set threshold, the pneumatic fan (14) should be started and the output power of the ventilation fan (15) should be increased.

2. The gas extraction system for ultra-long-distance high-gas tunnel earth pressure balance shield tunneling as described in claim 1, characterized in that: The end of the sealed tube is equipped with a gas concentration sensor for monitoring the gas concentration inside the sealed tube. The sealed tube is composed of several tube segments that are connected in sequence and sealed to each other. The length of each tube segment is 300-500mm.

3. The gas extraction system for ultra-long-distance high-gas tunnel earth pressure balance shield tunneling as described in claim 1, characterized in that: The gas extraction main pipe (10) is equipped with multiple extraction pumps (9) that discharge gas to the ground.

4. The gas extraction system for ultra-long-distance high-gas tunnel earth pressure balance shield tunneling as described in claim 1, characterized in that: The outlet end of the closed section (5) of the belt conveyor is provided with an open section (4) for transferring slag.

5. The gas extraction system for ultra-long-distance high-gas tunnel earth pressure balance shield tunneling as described in claim 1, characterized in that: The gas extraction branch pipe (11) is connected to the gas extraction main pipe (10) by a corrugated pipe or hose with adjustable length.

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