Gas pressure maintaining system and method for gas tunnel construction

Abstract

The present application relates to gas stratum underground space construction technical field, especially point to a kind of gas pressure maintaining system and pressure maintaining method for gas tunnel construction, solve the problem that equipment work interval gas, methane and other harmful gas concentration is too high in prior art, and cannot be diluted and absorbed in time processing.Provide a kind of gas pressure maintaining system and pressure maintaining method for gas tunnel construction, the system includes air cushion bin, air cushion bin is connected with gas inlet pipeline and exhaust pipeline, gas inlet pipeline is communicated with gas source pump station, exhaust pipeline is connected with combustible gas processing component, combustible gas processing component is communicated with emptying pipeline, emptying pipeline is communicated with shield machine outside.The beneficial effects generated by the present application are: this scheme is improved on the basis of traditional pressure maintaining exhaust scheme, first diluted by air, then treated by methane absorption device again, greatly reduce the methane concentration in the air cushion bin exhaust gas, solve the problem of high methane concentration in traditional scheme when driving in gas stratum, reduce the security risk of construction.

Description

Technical Field

[0001] This invention relates to the field of underground space construction technology in gas strata, and in particular to a gas pressure holding system and method for gas tunnel construction. Background Technology

[0002] Gas pressure maintenance is a crucial system for ensuring the safety of slurry balance shield tunneling machines during tunnel construction. The SAMSON system, in particular, dynamically regulates the pressure within the air cushion chamber through air intake and exhaust during shield construction, maintaining a pressure balance and ensuring stability during the construction process. However, in special geological formations such as gas tunnels rich in flammable and explosive gases like methane, failure to promptly detect and treat the emitted gases can lead to methane accumulation and explosions, jeopardizing construction safety. Currently, the main methods used in tunnel construction in hazardous gas formations include: 1. altering the design route; 2. employing open-cut construction; and 3. drilling boreholes on the surface to release the gases.

[0003] Patent CN 109469489 A discloses a method and device for treating harmful gases in the excavation chamber of a large-diameter slurry shield tunneling machine. An exhaust pipe is led out from the top of the excavation chamber and connected to a drainage pipe extending to the outside of the tunnel. An intake pipe is led out from the top of the air cushion chamber and connected to the shield machine's air compressor system. When the liquid level sensor in the excavation chamber detects a drop in the liquid level, indicating the accumulation of harmful gases, the shield machine stops operating. The shield machine's air compressor system pressurizes the air cushion chamber through the intake pipe, expelling the harmful gases through the exhaust pipe. While this method can remove harmful gases from the air cushion chamber, the discharged gases can lead to excessively high concentrations of methane, gas, and other harmful gases in the equipment's working area, which cannot be diluted and absorbed in time, thus affecting construction safety. Summary of the Invention

[0004] This invention proposes a gas pressure-maintaining system and method for gas tunnel construction, which solves the problem in the prior art where the concentration of harmful gases such as methane in the equipment working area is too high, making it impossible for the tunnel boring machine to continue working.

[0005] The technical solution of this invention is implemented as follows: The gas pressure-maintaining system for gas tunnel construction includes an air cushion chamber with an inlet and an outlet pipe. The inlet pipe connects to a gas source pump station, and the outlet pipe connects to a combustible gas treatment component, which in turn connects to a venting pipe connected to the outside of the tunnel boring machine (TBM). The gas source pump station is located outside the tunnel or at a location with low combustible gas concentration. The pump station introduces pressure-maintaining gas into the air cushion chamber through the inlet pipe. The pressure-maintaining gas in the air cushion chamber is then introduced into the combustible gas treatment component through the outlet pipe. The equal inlet and outlet flow rates within the air cushion chamber ensure dynamic pressure equilibrium. The pressure-maintaining gas discharged from the outlet pipe is diluted and absorbed by the combustible gas treatment component, reducing the concentration of combustible gases and mitigating safety hazards during gas tunnel construction.

[0006] The combustible gas treatment assembly includes a dilution branch connected in parallel with the exhaust pipe. The dilution branch is equipped with a control valve I for controlling the on / off state of the dilution branch. Opening the solenoid valve allows air to enter the exhaust pipe, diluting the pressurized gas within the exhaust pipe and reducing the concentration of combustible gas to a certain extent.

[0007] The combustible gas treatment assembly includes a gas absorption device. The inlet of the gas absorption device is connected to the exhaust pipe, and the outlet of the gas absorption device is connected to the venting pipe. The gas absorption device can absorb combustible gases in the gas, reduce the concentration of combustible gases, and discharge the pressurized gas with low combustible gas concentration through the venting pipe to ensure the construction safety of the gas tunnel.

[0008] The combustible gas treatment assembly also includes a gas storage tank. A gas absorption device is connected to the gas storage tank to form a circulation loop. The gas storage tank is equipped with a gas detector II for detecting the concentration of combustible gas within it. The gas detector II detects the concentration of combustible gas in the storage tank and uses this information to control the closure of the circulation loop. When the circulation loop is open, the pressurized gas circulates within the gas absorption device and the gas storage tank, passing through the gas absorption device multiple times. This allows the gas absorption device to absorb the combustible gas in the pressurized gas, thereby reducing its concentration. The pressurized gas with the low concentration of combustible gas is then discharged through a venting pipe, ensuring the safety of the gas tunnel construction.

[0009] The intake pipe, exhaust pipe, venting pipe, and circulation pipe are all equipped with control valves II for controlling the opening and closing of the pipes. The electric valves include an inlet electric valve, an outlet electric valve, an exhaust electric valve, and a circulation electric valve, which control the opening or closing of each pipe.

[0010] A silencer is arranged on the emptying pipeline; a fan and a first gas detector are arranged at the exhaust port of the emptying pipeline. The fan can disperse the pressure-holding gas discharged from the emptying pipeline, preventing the discharged combustible gas from accumulating again to ensure safety. Meanwhile, the first gas detector detects the real-time concentration of combustible gas in the gas tunnel, ensuring that the concentration of combustible gas in the gas tunnel is always kept at a safe value.

[0011] An intake valve for controlling intake flow is arranged on the intake pipeline, and an exhaust valve for controlling exhaust flow is arranged on the exhaust pipeline. The amount of gas entering and exiting the air cushion chamber is adjusted through the intake valve and the exhaust valve, so as to achieve dynamic balance of the pressure in the air cushion chamber.

[0012] The pressure holding system further comprises an upper computer, wherein the solenoid valve, the electric valve, the first gas detector and the second gas detector are all connected to the upper computer, and an alarm system is arranged in the upper computer. The first gas detector and the second gas detector transmit the detected combustible gas concentration data to the upper computer, and the data is compared with the set value in the upper computer, so that the opening or closing of the solenoid valve and the electric valve is controlled based on the comparison result, thereby realizing the control of the on-off of each pipeline.

[0013] A pressure holding method for a gas pressure holding system for gas tunnel construction, wherein a gas source pump station feeds pressure holding gas into an air cushion chamber through an intake pipeline, the pressure holding gas in the air cushion chamber is fed into a combustible gas processing assembly through an exhaust pipeline, and the intake flow and exhaust flow of the air cushion chamber are adjusted to enable the pressure in the air cushion chamber to reach dynamic balance; during the intake and exhaust processes of the air cushion chamber, the combustible gas in the air cushion chamber is discharged through the exhaust pipeline, which reduces the concentration of combustible gas in the air cushion chamber, avoids excessive concentration of combustible gas in the air cushion chamber, and ensures the safety of the air cushion chamber during construction.

[0014] Air is fed into the gas absorption device through a dilution branch to reduce the concentration of combustible gas in the pressure holding gas entering the gas absorption device; the pressure holding gas circulates multiple times between the gas absorption device and a gas storage tank, and the combustible gas in the pressure holding gas is absorbed by the gas absorption device, so as to reduce the concentration of combustible gas in the gas discharged from the gas absorption device.

[0015] A standard value A of combustible gas concentration in the gas tunnel, a shutdown value B of combustible gas concentration in the gas tunnel, and a power-off value C of combustible gas concentration in the gas tunnel are set through the upper computer; the detection value of combustible gas concentration in the gas tunnel is M, and the detection value of combustible gas concentration in the gas storage tank is N; specifically, the first gas detector detects the combustible gas concentration in the gas tunnel, and the second gas detector detects the combustible gas concentration in the gas storage tank.

[0016] When M < A, the concentration of combustible gas in the tunnel is at a normal level, the system performs normal cyclic exhaust, and keeps the pressure of the air cushion chamber stable; When A≤M<B, the concentration of combustible gas in the tunnel is higher than the standard value, the concentration is too high, the host computer alarms, the venting pipeline is closed, and the dilution branch and circulation pipeline are opened. When the concentration of combustible gas in the storage tank N<A, the dilution branch and venting pipeline are opened, and the circulation pipeline is closed. When B≤M<C, the concentration of combustible gas in the tunnel is higher than the shutdown value. If the concentration is too high, the host computer will alarm and the cutterhead will be stopped. The air intake pipe, exhaust pipe and venting pipe will be closed, and the dilution branch and circulation pipe will be opened. When the concentration of combustible gas in the gas storage tank N<A, the air intake pipe, exhaust pipe, venting pipe and dilution branch will be opened, and the circulation pipe will be closed. When M≥C, the concentration of combustible gas in the tunnel is higher than the power-off value. The concentration is too high, the host computer alarms, the cutterhead stops tunneling, the air intake pipe, exhaust pipe, venting pipe and dilution branch are all closed, and the entire equipment is powered off.

[0017] The beneficial effects of this invention are as follows: the gas source pump station introduces pressure-holding gas into the air cushion chamber through the air inlet pipeline, and the pressure-holding gas in the air cushion chamber is introduced into the combustible gas treatment component through the exhaust pipeline. The air inlet flow rate and exhaust flow rate of the air cushion chamber are adjusted by the air inlet valve and the exhaust valve to achieve dynamic balance of pressure in the air cushion chamber. After the pressure-holding gas discharged from the exhaust pipeline is diluted and absorbed by the combustible gas treatment component, the concentration of combustible gas in the pressure-holding gas is reduced, thereby reducing the safety hazards in gas tunnel construction.

[0018] Opening the solenoid valve allows air to enter the exhaust pipe, diluting the pressurized gas within and reducing the concentration of combustible gases to some extent. When the circulation pipe is open, the pressurized gas circulates between the gas absorption device and the storage tank. The gas absorption device absorbs the combustible gases within the pressurized gas, further reducing its concentration. The pressurized gas with the low concentration of combustible gases is then discharged through the venting pipe, ensuring the safety of gas tunnel construction. This scheme improves upon the traditional pressurized exhaust method by first diluting the gas with air and then subjecting it to secondary treatment by the gas absorption device. This significantly reduces the methane concentration in the gas discharged from the gas cushion chamber, solving the problem of excessively high methane concentrations during tunneling in gas-filled strata using traditional methods and reducing construction safety hazards.

[0019] This solution adds a fan, gas detector, and other equipment to the rear of the trailer, which can detect and treat the gas discharged to the rear of the trailer to prevent gas from accumulating at the rear. It also implements a program interlock on the host computer, which can quickly disconnect the connection with the air cushion chamber and perform circulation processing in case of an emergency. It has a fast response and a high safety factor.

[0020] The scheme is designed with a gas-electricity interlock protection program, which greatly improves the safety factor of shield tunneling in gas tunnels. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of a gas pressure maintaining system for gas tunnel construction according to the present invention.

[0023] Figure 2 This is a schematic diagram of the structure of Embodiment 2 of the present invention.

[0024] In the diagram: 1 is the air cushion chamber, 2 is the air source pump station, 3 is the air inlet valve, 4 is the inlet electric valve, 5 is the outlet electric valve, 6 is the exhaust valve, 7 is the solenoid valve, 8 is the gas absorption device, 9 is the exhaust electric valve, 10 is the circulation electric valve, 11 is the gas storage tank, 12 is the silencer, 13 is the fan, 14 is the gas detector I, 15 is the host computer, and 16 is the gas detector II. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1: A gas pressure-maintaining system for gas tunnel construction includes an air cushion chamber 1. The air cushion chamber 1 is connected to an air inlet pipe and an air outlet pipe. The air inlet pipe is connected to a gas source pump station 2, and the air outlet pipe is connected to a combustible gas treatment component. The combustible gas treatment component is connected to a venting pipe, which is connected to the outside of the tunnel boring machine. The gas source pump station 2 is located outside the tunnel or at a location with low combustible gas concentration. The air cushion chamber 1 contains slurry and pressure-maintaining gas. Specifically, the lower part of the air cushion chamber 1 contains slurry, and the upper part contains pressure-maintaining gas. Both the air inlet pipe and the air outlet pipe are connected to the upper part of the air cushion chamber 1.

[0027] Among them, the gas source pump station 2 introduces pressure-holding gas into the air cushion chamber 1 through the air inlet pipe, and the pressure-holding gas in the air cushion chamber 1 is discharged through the exhaust pipe. By adjusting the air inlet flow rate and exhaust flow rate of the air cushion chamber 1, the pressure in the air cushion chamber 1 is dynamically balanced. In addition, during the flow of the pressure-holding gas, the combustible gas in the air cushion chamber 1 can be discharged through the exhaust pipe along with the pressure-holding gas, thereby reducing the concentration of combustible gas in the air cushion chamber 1 and ensuring construction safety.

[0028] In addition, the pressurized gas discharged through the exhaust pipe is treated by a combustible gas treatment component. The combustible gas in the pressurized gas is diluted and absorbed by the combustible gas treatment component, reducing the concentration of combustible gas in the pressurized gas and keeping the concentration of combustible gas in the pressurized gas within a safe range. Then it is discharged through the venting pipe, which solves the problem of excessive methane concentration when tunneling in gas-filled strata in traditional methods and reduces the safety hazards of construction.

[0029] Example 2, based on Example 1, such as Figure 2 As shown, the combustible gas treatment component includes a dilution branch connected in parallel with the exhaust pipe. The dilution branch is connected to the external air of the tunnel and is equipped with a control valve I for controlling the on / off state of the dilution branch. The outlets of both the exhaust pipe and the dilution branch are connected to the venting pipe. The exhaust pipe introduces pressurized gas into the venting pipe, while the dilution branch introduces air into the venting pipe. The pressurized gas and air mix and are then discharged through the venting pipe. The mixing of air and pressurized gas dilutes the pressurized gas, thereby reducing the concentration of combustible gas discharged through the venting pipe to a certain extent. This ensures that the concentration of combustible gas inside the gas tunnel remains at a low level, thus guaranteeing the construction safety of the gas tunnel.

[0030] In addition, the control valve I is a solenoid valve 7; the solenoid valve 7 can control the opening and closing of the dilution branch. Specifically, when the solenoid valve 7 is open, air enters the dilution branch through the solenoid valve 7 and mixes and dilutes with the pressurized gas to reduce the concentration of combustible gas; when the solenoid valve 7 is closed, the dilution branch is closed.

[0031] Example 3, based on Example 1, includes a combustible gas treatment component comprising a gas absorption device 8. The inlet of the gas absorption device 8 is connected to an exhaust pipe, and the outlet of the gas absorption device 8 is connected to a venting pipe. The pressurized gas discharged from the exhaust pipe enters the gas absorption device 8, which absorbs the combustible gas within it, reducing its concentration. This allows the venting pipe to discharge pressurized gas with a lower concentration of combustible gas, ensuring the safety of the gas tunnel. In this example, the gas absorption device 8 is a methane absorption device. The combustible gas in the pressurized gas is methane. After entering the methane absorption device, it absorbs the methane, reducing its concentration and mitigating safety hazards in the gas tunnel.

[0032] Example 4, based on Example 3, the combustible gas treatment component further includes a gas storage tank 11. The gas absorption device 8 is connected to the gas storage tank 11 to form a circulation loop. When the concentration of combustible gas in the gas discharged from the venting pipe is high, the venting pipe is closed, and the gas absorbed and treated by the gas absorption device 8 is introduced into the gas storage tank 11. Then, the gas storage tank 11 re-introduces the gas absorption device 8 for secondary absorption treatment of the combustible gas until the concentration of combustible gas in the gas storage tank 11 is reduced to the standard value. Then, the venting pipe is opened, and the gas treated by the gas absorption device 8 is discharged from the venting pipe, ensuring that the concentration of combustible gas in the gas discharged from the venting pipe is always lower than the standard value, thereby keeping the concentration of combustible gas in the gas tunnel at a low level and reducing the safety hazards in the gas tunnel.

[0033] Furthermore, the gas storage tank 11 is equipped with a gas detector II 16 for detecting the concentration of combustible gas inside the gas storage tank 11. The gas detector II 16 detects the concentration of methane inside the gas storage tank 11 and controls the opening or closing of the circulation pipeline based on this. Specifically, when the methane concentration detected by the gas detector II 16 is greater than the standard value, the circulation pipeline is opened; when the methane concentration detected by the gas detector II 16 is less than the standard value, the circulation pipeline is closed.

[0034] Example 5, based on Example 2, such as Figure 1 As shown, the combustible gas treatment assembly includes a gas absorption device 8 and a gas storage tank 11. The gas absorption device 8 and the gas storage tank 11 are connected end to end to form a circulation pipeline. The inlet of the gas absorption device 8 is connected to the exhaust pipeline and the dilution pipeline, and the outlet of the gas absorption device 8 is connected to the venting pipeline. In this embodiment, the pressurized gas in the exhaust pipeline and the air in the dilution branch are simultaneously introduced into the gas absorption device 8. After being processed by the gas absorption device 8, the gas is discharged from the venting pipeline. The dilution branch performs primary treatment on the pressurized gas by dilution to reduce the concentration of combustible gas. The gas absorption device 8 performs secondary treatment on the pressurized gas by combustible gas absorption to further reduce the concentration of combustible gas, so that the venting pipeline discharges gas with a lower concentration of combustible gas.

[0035] In addition, when the concentration of combustible gas discharged from the venting pipeline exceeds the standard value, the venting pipeline is closed, and the gas discharged from the gas absorption device 8 is temporarily stored in the gas storage tank 11. Then, the gas storage tank 11 re-enters the gas absorption device 8 for secondary absorption treatment. This cycle is repeated multiple times until the concentration of combustible gas in the gas storage tank 11 is less than the standard value. At this point, the venting pipeline is opened, thus ensuring that the concentration of combustible gas in the gas discharged from the venting pipeline is always kept below the standard value. This keeps the concentration of combustible gas in the gas tunnel within a safe range and effectively reduces the safety hazards during construction in the gas tunnel.

[0036] Example 6, based on Example 4 or Example 5, includes control valves II for controlling the on / off state of the intake, exhaust, venting, and circulation pipelines. In this example, the control valves II are electric valves. Specifically, the intake pipeline has an inlet electric valve 4; the exhaust pipeline has an outlet electric valve 5; the venting pipeline has an exhaust electric valve 9; and the circulation pipeline has a circulation electric valve 10, located between the outlet of the gas absorption device 8 and the inlet of the gas storage tank 11. By opening or closing the electric valves, the on / off state of the pipelines containing the electric valves can be controlled, thus achieving automated system control.

[0037] Furthermore, a silencer 12 is installed on the venting pipeline. The silencer 12 can effectively reduce the noise generated during gas emission and lower the noise intensity, thereby protecting the ears and health of employees. A fan 13 and a gas detector I 14 are installed at the exhaust port of the venting pipeline. The fan 13 disperses the gas discharged from the venting pipeline, preventing methane gas from accumulating in the trailer's rear area, thus improving the safety of equipment operation to a certain extent. The gas detector I 14 can monitor the methane concentration in the gas tunnel in real time, allowing staff to assess the safety of construction within the tunnel.

[0038] Furthermore, the gas pressure maintaining system also includes a host computer 15, and solenoid valve 7, electric valve, gas detector I 14, and gas detector II 16 are all connected to the host computer 15. The concentration data of combustible gas in the gas tunnel detected by gas detector I 14 and the concentration data of combustible gas in the gas storage tank 11 detected by gas detector II 16 can be transmitted to the host computer 15. The host computer 15 controls the opening or closing of solenoid valve 7 and electric valve based on the concentration data of combustible gas, thereby controlling the on / off of the pipeline where the electric valve is located, realizing the switching of the working state of the gas pressure maintaining system, improving the automation level of the system, and making it easier for operators to use the gas pressure maintaining system.

[0039] Furthermore, an intake valve 3 is provided on the intake pipe to control the intake airflow, and an exhaust valve 6 is provided on the exhaust pipe to control the exhaust flow. The intake valve 3 can adjust the gas flow rate entering the air cushion chamber 1, and the exhaust valve 6 can adjust the flow rate of the pressure-holding gas discharged from the air cushion chamber 1. The two work together to achieve dynamic balance of pressure in the air cushion chamber 1 and keep it within a constant range.

[0040] Example 7 differs from Example 6 in that control valve II is provided on the intake pipe, exhaust pipe, venting pipe, and circulation pipe. The control valve II is a manual ball valve. The opening or closing of the manual ball valve controls the on / off state of the pipe where the manual ball valve is located. Specifically, when the host computer 15 detects that the methane concentration in the gas tunnel exceeds the standard through the gas detector I14, the staff controls the manual ball valve to adjust the on / off state of each pipe.

[0041] Example 8, based on Example 6, provides a pressure-maintaining method for a gas pressure-maintaining system used in gas tunnel construction. A gas source pump station 2 introduces pressure-maintaining gas into the air cushion chamber 1 through an inlet pipe. The pressure-maintaining gas in the air cushion chamber 1 is then introduced into a combustible gas treatment component through an exhaust pipe. The inlet and exhaust flow rates of the air cushion chamber 1 are adjusted to achieve dynamic pressure balance within the chamber. During the inlet and exhaust processes of the air cushion chamber 1, the combustible gas within the chamber can be discharged through the exhaust pipe, reducing the concentration of combustible gas within the chamber and preventing excessively high concentrations, thus ensuring the safety of the air cushion chamber 1 during construction.

[0042] Furthermore, air is introduced into the gas absorption device 8 through the dilution branch to reduce the concentration of combustible gas in the pressurized gas entering the gas absorption device 8; the pressurized gas circulates multiple times between the gas absorption device 8 and the gas storage tank 11, absorbing the combustible gas in the pressurized gas through the gas absorption device 8, thereby reducing the concentration of combustible gas in the gas discharged from the gas absorption device 8.

[0043] Furthermore, the host computer 15 sets the standard value A for combustible gas concentration in the gas tunnel, the shutdown value B for combustible gas concentration in the gas tunnel, and the power-off value C for combustible gas concentration in the gas tunnel; the detection value M for combustible gas concentration in the gas tunnel, and the detection value N for combustible gas concentration in the gas storage tank 11; in this embodiment, the standard value for combustible gas concentration is 0.3%, the shutdown value is 0.5%, and the power-off value is 1%. When M < 0.3%, the concentration of combustible gas in the tunnel is within the normal range, the system circulates and exhausts normally, and the pressure of air cushion chamber 1 remains stable. When 0.3%≤M<0.5%, the concentration of combustible gas in the tunnel is higher than the standard value, indicating a high concentration. The host computer 15 alarms, the venting pipeline is closed, and the dilution branch and circulation pipeline are opened. When the concentration of combustible gas N in the gas storage tank 11 is less than 0.3%, the dilution branch and venting pipeline are opened, and the circulation pipeline is closed. Specifically, the exhaust electric valve 9 is closed, and the solenoid valve 7 and circulation electric valve 10 are opened. The gas, after being diluted by the dilution branch and absorbed by the gas absorption device 8, enters the gas storage tank 11 for temporary storage. Then, it is circulated back into the gas absorption device 8 from the gas storage tank 11 for secondary absorption until the concentration of combustible gas N in the gas storage tank 11 is less than 0.3%. At this point, the circulation electric valve 10 is closed, and the solenoid valve 7 and exhaust electric valve 9 are opened, and the gas is discharged from the venting pipeline. When 0.5% ≤ M < 1%, the concentration of combustible gas in the tunnel is higher than the shutdown value. Due to the excessively high concentration, the host computer 15 alarms and interlocks to stop the cutterhead excavation. The intake, exhaust, and venting pipelines are all closed, while the dilution branch and circulation pipeline are opened. When the concentration of combustible gas N in the gas storage tank 11 is < 0.3%, the intake, exhaust, venting, and dilution branch pipelines are opened, and the circulation pipeline is closed. Specifically, the inlet electric valve 4, outlet electric valve 5, and exhaust electric valve 9 are all closed, while the solenoid valve 7 and circulation electric valve 10 are opened. When the gas is opened, the pressure-holding gas in the air cushion chamber 1 stops being discharged, the cutterhead stops being used, and the gas after being diluted by the dilution branch and absorbed by the gas absorption device 8 enters the gas storage tank 11 for temporary storage. Then, the gas is circulated from the gas storage tank 11 back into the gas absorption device 8 for secondary absorption until the concentration of combustible gas N in the gas storage tank 11 is <0.3%. At this time, the circulation electric valve 10 is closed, and the inlet electric valve 4, outlet electric valve 5, solenoid valve 7 and exhaust electric valve 9 are opened. The gas is discharged from the exhaust pipeline, the cutterhead interlock is released, the system is running normally, and tunneling begins. When M ≥ 1%, the concentration of combustible gas in the tunnel exceeds the power-off threshold, indicating an excessively high concentration. The host computer alarm (15) activates, the cutterhead stops tunneling, and the intake, exhaust, venting, and dilution branches are all shut off. The entire equipment is powered off. Specifically, inlet electric valve 4, outlet electric valve 5, solenoid valve 7, exhaust electric valve 9, and circulation electric valve 10 close, triggering the power interlock control and causing a complete power outage. Tunneling can only resume after the methane concentration M in the tunnel returns to normal.

[0044] 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, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A pressure-maintaining method for a gas pressure-maintaining system used in gas tunnel construction, comprising an air cushion chamber (1), wherein the air cushion chamber (1) is connected to an air inlet pipe and an air outlet pipe, the air inlet pipe being connected to a gas source pump station (2), characterized in that, The exhaust pipeline is connected to the combustible gas treatment assembly, the combustible gas treatment assembly is communicated with the emptying pipeline, and the emptying pipeline is communicated with the outside of the shield tunneling machine; The combustible gas treatment assembly includes a dilution branch connected in parallel with the exhaust pipeline, and a control valve I for controlling the on-off of the dilution branch is arranged on the dilution branch; The combustible gas treatment assembly includes a gas absorption device (8), an inlet of the gas absorption device (8) is communicated with the exhaust pipeline, and an outlet of the gas absorption device (8) is communicated with the emptying pipeline; The combustible gas treatment assembly further includes a gas storage tank (11), the gas absorption device (8) and the gas storage tank (11) are connected to form a circulation loop, and a gas detector II (16) for detecting the concentration of combustible gas in the gas storage tank (11) is arranged on the gas storage tank (11); An air source pumping station (2) feeds pressure-holding gas into an air cushion chamber (1) through an air intake pipeline, the pressure-holding gas in the air cushion chamber (1) is fed into the combustible gas treatment assembly through the exhaust pipeline, and the air intake flow rate and exhaust flow rate of the air cushion chamber (1) are adjusted to make the pressure in the air cushion chamber (1) reach dynamic balance; Air is fed into the gas absorption device (8) through the dilution branch to reduce the concentration of combustible gas in the pressure-holding gas entering the gas absorption device (8); the pressure-holding gas circulates multiple times between the gas absorption device (8) and the gas storage tank (11), and the combustible gas in the pressure-holding gas is absorbed by the gas absorption device (8), so as to reduce the concentration of combustible gas in the gas discharged from the gas absorption device (8); A standard value of combustible gas concentration in a gas tunnel is set as A through an upper computer (15), a shutdown value of combustible gas concentration in the gas tunnel is set as B, and a power-off value of combustible gas concentration in the gas tunnel is set as C; the detection value of combustible gas concentration in the gas tunnel is M, and the detection value of combustible gas concentration in the gas storage tank (11) is N; When M<A, the combustible gas concentration in the tunnel is at a normal level, the system performs normal circulating exhaust, and keeps the pressure of the air cushion chamber (1) stable; When A≤M<B, the combustible gas concentration in the tunnel is higher than the standard value, which means the concentration is relatively high, the upper computer gives an alarm, the emptying pipeline is closed, the dilution branch and the circulation pipeline are opened; when the combustible gas concentration N in the gas storage tank (11) is lower than A, the dilution branch and the emptying pipeline are opened, and the circulation pipeline is closed; When B≤M<C, the combustible gas concentration in the tunnel is higher than the shutdown value, which means the concentration is too high, the upper computer gives an alarm and interlocks the cutter head to stop tunneling, the air intake pipeline, the exhaust pipeline and the emptying pipeline are all closed, the dilution branch and the circulation pipeline are opened; when the combustible gas concentration N in the gas storage tank (11) is lower than A, the air intake pipeline, the exhaust pipeline, the emptying pipeline and the dilution branch are opened, and the circulation pipeline is closed; When M≥C, the combustible gas concentration in the tunnel is higher than the power-off value, which means the concentration is extremely high, the upper computer gives an alarm, the cutter head stops tunneling, the air intake pipeline, the exhaust pipeline, the emptying pipeline and the dilution branch are all closed, and the whole equipment is powered off.

2. The pressure-maintaining method of the gas pressure-maintaining system for gas tunnel construction according to claim 1, characterized in that, Control valves II for controlling the on-off of the pipelines are respectively arranged on the air intake pipeline, the exhaust pipeline, the emptying pipeline and the circulation pipeline.

3. The pressure-maintaining method of the gas pressure-maintaining system for gas tunnel construction according to claim 1 or 2, characterized in that, A silencer (12) is arranged on the emptying pipeline; a fan (13) and a gas detector I (14) are arranged at an exhaust port of the emptying pipeline.

4. The pressure-maintaining method of the gas pressure-maintaining system for gas tunnel construction according to claim 3, characterized in that, An intake valve (3) for controlling the intake air volume is provided on the intake pipe, and an exhaust valve (6) for controlling the exhaust flow is provided on the exhaust pipe.

5. The pressure-maintaining method of the gas pressure-maintaining system for gas tunnel construction according to claim 4, characterized in that, It also includes a host computer (15), control valve I is a solenoid valve (7), control valve II is an electric valve, solenoid valve (7), electric valve, gas detector I (14) and gas detector II (16) are all connected to the host computer (15), and the host computer (15) is equipped with an alarm system.

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