Fireproof and smoke-proof ventilation system and method for long-distance underground tunnel

Abstract

The invention discloses a long-distance underground tunnel fireproof and smoke-proof ventilation system and method.The internal space of a tunnel is divided into a plurality of adjacent fireproof subareas, fireproof walls are arranged between the fireproof subareas and on the outer side of the fireproof subarea on the outermost side, and fireproof doors capable of being opened and closed and fireproof air ports capable of being opened and closed are arranged on the fireproof walls; an excess pressure valve is further arranged at the fireproof tuyere and only allows one-way opening, and the allowed airflow flows from the center part of the tunnel to the outer part of the tunnel; an air inlet machine room is connected to the outer portion of the tunnel, a fan is arranged in the air inlet machine room, the output end of the fan is connected with a fireproof air pipe, fresh air outlets are formed in the tail ends of branch pipes, located in all the fireproof subareas, of the fireproof air pipe, and fireproof valves used for controlling on-off are arranged on all the branch pipes of the fireproof air pipe. The scheme has the dual functions of smoke prevention and ventilation, and can meet the requirements of smoke prevention and post-disaster ventilation of small-section and long-distance tunnel engineering at ordinary times.

Description

Technical Field

[0001] The present invention belongs to the technical field of tunnel ventilation, and in particular relates to a fire and smoke prevention ventilation system and method for a long-distance underground tunnel. Background Art

[0002] Conventional mechanical smoke control systems typically consist of air supply ducts with a fire resistance rating of at least one hour, pressurized air supply fans, fire dampers, and air outlets. These systems typically serve areas such as stairwells, antechambers, refuge rooms, and escape corridors. Conventional mechanical ventilation systems typically consist of air ducts, fans, dampers, and air outlets, and typically serve any room requiring mechanical ventilation. In existing tunnel projects, conventional mechanical smoke control systems and conventional mechanical ventilation systems are typically installed and operated separately.

[0003] For some special work areas such as laboratories and clean rooms, tunnels are currently opened in the mountains to obtain the required special working environment in the middle of the mountain, and the required special work areas are constructed in the interior space of the tunnel. For this type of tunnel project with small cross-section and long tunnel, the interior space of the tunnel needs to have functions such as personnel activities and fire evacuation. In addition, since the interior space of the tunnel usually has multiple fire protection zones and the space requires a large number of process and electromechanical installation pipelines, the conventional smoke control and ventilation mechanical systems with dispersed settings occupy too much space and are difficult to meet the space requirements of narrow cross-sections. In addition, due to the extremely long distance between the ventilation openings in long-distance tunnels, the conventional mechanical smoke control systems and conventional mechanical ventilation systems have poor airtightness and are difficult to meet the needs of long-distance air transportation. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a fire and smoke prevention ventilation system and method for long-distance underground tunnels, so as to solve the problem that the existing tunnel ventilation scheme cannot be applied to the special engineering needs of small cross-sections and long distances, and to achieve normal ventilation and air exchange effects for spaces where people stay for a long time in long-distance underground tunnels when the tunnel ventilation openings are located far away. When a fire occurs in the tunnel space, it can provide a mechanical smoke prevention function, and after the fire is extinguished, it can serve as an air supply system for post-disaster ventilation to replace the air in the tunnel space.

[0005] According to the technical solution of the present invention, the present invention provides a fire and smoke prevention ventilation system for a long-distance underground tunnel, including a tunnel, wherein the internal space of the tunnel is divided into multiple adjacent fire partitions, wherein one or more fire partitions in the central part of the tunnel are special working areas, and the remaining fire partitions are tunnel separation areas; fire walls are arranged between the fire partitions and on the outside of the outermost fire partition, and openable and closable fire doors and openable and closable fire vents are arranged on the fire walls, and a residual pressure valve is also arranged at the fire vent, which only allows one-way opening and allows air flow from the central part of the tunnel to the outer part of the tunnel; an air intake room is connected to the outer part of the tunnel, and a fan is arranged in the air intake room, and the output end of the fan is connected to a fire duct, and the fire duct branches to form multiple branches and extend from the air intake room to each fire partition respectively, and the ends of the branches of the fire duct in each fire partition are provided with fresh air outlets, and each branch of the fire duct is provided with a fire damper for controlling on and off.

[0006] In some embodiments, a regulating valve is further provided in the branch pipe where the fresh air outlet of the special working area is located.

[0007] In some embodiments, each fire compartment is provided with a smoke detector.

[0008] In some embodiments, the fireproof air duct is a fully welded structure.

[0009] In some embodiments, the air inlet room is provided with air inlet louvers, and the input end of the fan is connected to the outside through the air inlet louvers.

[0010] In some embodiments, the fan is a centrifugal fan unit composed of one or more centrifugal fans, and / or the fresh air outlet is a single-layer louver air outlet.

[0011] In some embodiments, the tunnels are T-shaped, Y-shaped, straight-shaped, cross-shaped, radial-shaped, or staggered to form a network.

[0012] In some embodiments, in addition to the fire walls adjacent to the special work area, other fire walls are also provided with openable and closable fire shutter doors.

[0013] In some embodiments, a smoke exhaust valve is further provided in the branch pipe where the fresh air outlet of the tunnel separation area is located.

[0014] According to the technical solution of the present invention, the present invention also provides a fire and smoke prevention ventilation method for a long-distance underground tunnel, which is implemented using the fire and smoke prevention ventilation system for a long-distance underground tunnel of the present invention. In this method, except for the fire walls adjacent to the special working area, the other fire walls are also provided with openable and closable fire shutter doors, and a smoke exhaust valve is also provided in the branch pipe where the fresh air outlet of the tunnel separation area is located; The fire and smoke prevention ventilation method for long-distance underground tunnels includes three working modes, corresponding to the tunnel's normal ventilation conditions, tunnel fire and smoke prevention ventilation conditions, and tunnel post-disaster ventilation conditions; Under normal ventilation conditions in the tunnel, fire doors are normally closed when not in use, fire vents are open, fire shutter doors are open, fire dampers are open, and smoke exhaust dampers are closed. Fresh air is delivered to the special working area through fans and fire ducts. The fresh air delivered to the special working area is pressed into the fire compartments adjacent to the special working area through the residual pressure valves of the fire vents. The fresh air then flows outward through each fire compartment one by one, and is finally discharged outside the tunnel through the fire vents of the outermost fire compartment. When a fire occurs in a certain fire compartment, the tunnel enters the fire smoke ventilation mode, the fire damper corresponding to the fire compartment where the fire occurs is closed, the fire shutter door and fire vent adjacent to the fire compartment where the fire occurs are closed, and the smoke exhaust damper corresponding to the fire compartment where the fire does not occur is opened; fresh air is sent into the fire compartment where the fire does not occur through the fan and fire duct, and the residual pressure valve is used to ensure that the fire compartment where the fire does not occur is in a positive pressure state to prevent the smoke in the fire compartment where the fire occurs from entering the fire compartment where the fire does not occur; When the fire in the fire compartment where the fire occurred has been extinguished, the tunnel enters the post-disaster ventilation condition, the fire damper opens, the smoke exhaust valve corresponding to the fire compartment where no fire occurred is closed, and the smoke exhaust valve and fire vent corresponding to the fire compartment where the fire has been extinguished are opened; fresh air is sent into the fire compartment where the fire has been extinguished through the fan and the fire duct. Based on the one-way conduction characteristic of the residual pressure valve, the smoke in the fire compartment where the fire has been extinguished gradually flows to the fire vent downstream of the air flow due to the influence of the pressure gradient, and finally the smoke is discharged to the outside of the tunnel and fresh air fills each fire compartment.

[0015] Compared with the prior art, the beneficial technical effects of the present invention are as follows: The long-distance underground tunnel fire and smoke prevention ventilation system and method of the present invention has the dual functions of a mechanical smoke prevention system and a mechanical ventilation system, and occupies a small space, and can adapt to the ventilation needs of small-section, long-distance tunnel projects in normal times, smoke prevention and post-disaster situations; based on the particularity of slow air flow deep in long-distance tunnels, the flow of airflow in this solution is pressure-driven. If no pressure is formed, the air flow will be very slow, and the air quality deep in the tunnel cannot meet the needs of personnel working long-term inside; in the event of a fire somewhere in the tunnel, the area can be separated from other areas, and positive pressure can be formed in other areas to prevent harmful smoke generated by the fire from entering other areas, thereby realizing smoke prevention function and providing protection for the safe evacuation of personnel; it is further preferred to adopt a fully welded structure to achieve a highly sealed system configuration, which can effectively reduce the air volume loss during long-distance air transportation, improve the transportation efficiency of the ventilation system, and reduce the energy consumption of the fan. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic top view of the system structure provided by the present invention.

[0017] Description of reference numerals in the accompanying drawings: 1. Tunnel; 2. Fan; 3. Fireproof air duct; 4. Smoke exhaust damper; 5. Fresh air outlet; 6. Fireproof air outlet; 7. Residual pressure valve; 8. Fire damper; 9. Air supply room; 10. Special work area; 11. Exhaust outlet; 12. Air inlet louver; 13. Control valve; 14. Fireproof rolling shutter door; 15. Smoke detector; 16. Fire door. DETAILED DESCRIPTION

[0018] The present invention provides a fire and smoke prevention ventilation system and method for long-distance underground tunnels, which solves the problem that existing tunnel ventilation solutions are not suitable for special engineering needs of small-section and long-distance projects. It can provide normal ventilation and air exchange effects for spaces where people stay for a long time in long-distance underground tunnels even when the tunnel ventilation openings are located far away. When a fire occurs in the tunnel space, it can provide a mechanical smoke prevention function. After the fire is extinguished, it can serve as an air supply system for post-disaster ventilation to replace the air in the tunnel space.

[0019] See also Figure 1 The present invention provides a long-distance underground tunnel fire and smoke prevention ventilation system, comprising a tunnel 1. The interior of the tunnel 1 is divided into multiple adjacent fire compartments, each of which is capable of forming a relatively independent area. One or more fire compartments in the central portion of the tunnel 1 serve as special work areas 10, which are areas used for work and experiments within the tunnel, such as laboratories and clean rooms. The remaining fire compartments serve as tunnel partitions, primarily for passage.

[0020] Firewalls are installed between the fire compartments and outside the outermost fire compartment. These firewalls are equipped with openable and closable fire doors 16 and openable and closable fire vents 6. Fire vents 6 are also equipped with residual pressure valves 7. Residual pressure valves 7 are designed to allow only one-way opening (or one-way flow), and they allow airflow from the center of tunnel 1 toward the outer portion of tunnel 1. As a supplementary note, the residual pressure valves are existing devices, and their one-way flow direction can be limited, for example, by their installation orientation.

[0021] An air inlet room 9 is connected to the outer part of the tunnel 1, and a fan 2 is installed in the air inlet room 9. The output end of the fan 2 is connected to a fireproof air duct 3. The fireproof air duct 3 branches into multiple branches and extends from the air inlet room 9 to each fire compartment. The ends of the branches of the fireproof air duct 3 located in each fire compartment are provided with fresh air outlets 5. The fresh air outlet 5 is, for example, a single-layer louver air outlet. A fire damper 8 for controlling the on and off is provided on each branch of the fireproof air duct 3.

[0022] More specifically, taking deep earth projects such as underground laboratories as an example, tunnel 1 is opened in the mountain, extending from a low altitude outside the mountain to the inside of the mountain, reaching the location required for the construction of a special working area 10, which is covered by thicker mountain rocks, and then the tunnel 1 is extended to the outside of the mountain with or without changing direction. Generally, there are at least two tunnel paths on both sides outside the special working area 10. For example, when viewed from above, the tunnel 1 is in a T-shape, a Y-shape, a straight line, a cross, a radial line, or a staggered network. Figure 1 In the illustrated structure, tunnel 1 is T-shaped. The central area, where the longitudinal and transverse tunnels intersect, constitutes a special work area 10. Both the longitudinal and transverse tunnels outside of special work area 10 have multiple fire compartments. The outermost fire vents 6 serve as exhaust vents 11, which can communicate with the outside world. The air intake room 9, for example, is located outside the mountain and can communicate with the outside world. The outermost end of tunnel 1, for example, also extends outside the mountain and can communicate with the outside world.

[0023] Furthermore, a regulating valve 13 is installed in the branch pipe where the fresh air outlet 5 of the special work area 10 is located. Fan 2 is a centrifugal fan unit composed of one or more centrifugal fans (more specifically, high-temperature resistant fixed-frequency centrifugal fans). The ventilation volume required within tunnel 1 can be adjusted by varying the number of workstations and / or the opening of regulating valve 13 (or other valves on the output side of fan 2). The air intake room 9 is equipped with air inlet louvers 12, through which the input of fan 2 is connected to the outside world. Of course, the input of fan 2 is not limited to this, and can, for example, be input through a pipeline, with optional filtering components installed on the input side.

[0024] Preferably, each fire protection zone is provided with a smoke detector 15, so that a fire situation can be automatically and promptly detected, and further the opening and closing of each valve, door and air vent can be automatically controlled in conjunction with the control system.

[0025] Preferably, the fireproof air duct 3 is a fully welded structure. For conventional ventilation systems on the ground, due to the low internal pressure, flange docking with sealing gaskets and bolt fastening is usually adopted. This connection method has poor sealing performance and is difficult to meet the air leakage level requirements required for long-distance underground tunnels. Full welding means that all joints in the pipeline system are fully welded, which has high airtightness and can meet the extremely low air leakage level during long-distance air transportation. At the same time, it can avoid the hidden dangers of air leakage under smoke-proof conditions. Accordingly, each valve adopts a highly sealed product. This solution adopts a highly sealed system configuration, which can effectively reduce the air volume loss during long-distance air transportation, improve the transportation efficiency of the ventilation system, and reduce the energy consumption of the fan.

[0026] Preferably, except for the firewall adjacent to the special work area 10, all other firewalls are equipped with openable and closable fire shutter doors 14. The special work area 10 is surrounded by firewalls (or tunnel walls), and personnel can only pass through the fire doors 16 provided in the firewalls. Other areas can also be accessed through the door openings of the fire shutter doors 14. Considering that long-distance tunnel traversal may require vehicles or other means of transportation, the fire shutter doors 14 are normally open. When opened, they directly connect two adjacent fire compartments. In the event of a fire, specific fire shutter doors 14 are lowered and closed.

[0027] Preferably, a smoke exhaust valve 4 is also provided in the branch pipe where the fresh air outlet 5 in the tunnel separation area is located, more specifically a highly sealed normally closed smoke exhaust valve, which is opened only when air circulation is required, further ensuring the accuracy and airtightness of the fresh air flow pattern in the system.

[0028] Based on the above-mentioned long-distance underground tunnel fire and smoke prevention ventilation system of the present invention, the present invention provides a long-distance underground tunnel fire and smoke prevention ventilation method, which adopts the preferred system structure of the present invention, that is, in addition to the fire wall adjacent to the special working area 10, other fire walls are also provided with openable and closable fire shutter doors 14, and a smoke exhaust valve 4 is also provided in the branch pipe where the fresh air outlet 5 in the tunnel separation area is located; the structures of other aspects can be added or adjusted as needed.

[0029] The fire and smoke prevention ventilation method for a long-distance underground tunnel of the present invention includes three working modes, which respectively correspond to the normal ventilation working conditions of the tunnel, the fire and smoke prevention ventilation working conditions of the tunnel, and the post-disaster ventilation working conditions of the tunnel.

[0030] Under normal ventilation conditions in the tunnel, the fire door 16 is normally closed when not in use, the fire vent 6 is open, the fire shutter door 14 is open, the fire damper 8 is open, and the smoke exhaust valve 4 is closed; fresh air is sent into the special working area 10 through the fan 2 and the fire duct 3, and the fresh air sent into the special working area 10 is pressed into the fire partition adjacent to the special working area 10 through the residual pressure valve 7 of the fire vent 6, and the fresh air then flows outward through the fire partitions one by one, and is finally discharged to the outside of the tunnel 1 through the fire vent 6 of the outermost fire partition.

[0031] When a fire occurs in a certain fire compartment, the tunnel enters the fire smoke and ventilation condition, the fire damper 8 corresponding to the fire compartment where the fire occurs is closed, and the fire shutter door 14 and the fire air vent 6 adjacent to the fire compartment where the fire occurs are closed, so that the fire compartment where the fire occurs is independently separated; the smoke exhaust valve 4 corresponding to the fire compartment where the fire does not occur is opened; fresh air is sent into the fire compartment where the fire does not occur through the fan 2 and the fire duct 3, and the residual pressure valve 7 ensures that the fire compartment where the fire does not occur is in a positive pressure state (more specifically, a positive pressure state of 25Pa to 30Pa) to prevent the smoke in the fire compartment where the fire occurs from entering the fire compartment where the fire does not occur, so as to help people in the tunnel to take refuge and evacuate.

[0032] As a supplementary explanation, the one-way conduction and opening of the residual pressure valve 7 are automatically realized based on the air pressure. The fire vent 6 is installed synchronously with the residual pressure valve 7. The operating logic of the fire vent 6 is that when a fire occurs in a certain partition, the fire vent 6 of the partition is closed. After the fire vent 6 is closed, the partition is isolated; normally, the fire vent 6 is normally open, and air can flow (in a specific direction) through the residual pressure valve 7 and the fire vent 6. Assume that a fire breaks out in Zone B of the three adjacent zones A, B, and C. Zone B will be isolated, and fresh air will be introduced to Zones A and C. If there is an area on the side of Zones A and C facing the one-way direction of the residual pressure valve 7 where no fire has occurred, the newly added air will flow toward that side and will not enter Zone B. If Zones A and C are at the very end of the tunnel or the very end of the one-way direction of the residual pressure valve 7, then this newly added air will be retained in Zones A and C, and the air pressure in Zones A and C will increase until no more air can flow in. Because the air pressure in Zones A and C is higher than that in Zone B, and the fire doors 16, fire shutter doors 14, and fire vents 6 on both sides of Zone B are all closed, it can be ensured that the fire smoke in Zone B cannot enter Zones A and C. Under the tunnel fire smoke prevention and ventilation conditions, people in Tunnel 1 can evacuate to both sides of the fire zone where the fire has occurred, and ultimately evacuate to the outside of Tunnel 1.

[0033] When the fire in the fire compartment where the fire occurred has been extinguished, the tunnel enters the post-disaster ventilation condition, the fire damper 8 is opened, the smoke exhaust valve 4 corresponding to the fire compartment where no fire occurred is closed, the smoke exhaust valve 4 corresponding to the fire compartment where the fire has been extinguished is opened, the fire vent 6 is opened, and the fire shutter door 14 remains closed; fresh air is sent into the fire compartment where the fire has been extinguished through the fan 2 and the fire duct 3. Based on the unidirectional conduction characteristic of the residual pressure valve 7, the smoke in the fire compartment where the fire has been extinguished gradually flows to the fire vent 6 downstream of the air flow due to the influence of the pressure gradient, and finally the smoke is discharged to the outside of the tunnel 1, and the fresh air fills each fire compartment.

[0034] As a supplementary explanation, since this is a post-disaster working condition and there are no people, the harmful gases will not cause harm to people during the discharge process through the downstream partition of the airflow. People will not enter Tunnel 1 until the fresh air replacement is completed to resume normal working conditions.

[0035] Preferably, each fire compartment is equipped with a smoke detector 15, and the system and method are automatically controlled by a control system. When a fire occurs in a fire compartment, the smoke detector 15 will issue an alarm, causing the control system to automatically implement the corresponding process (tunnel fire smoke prevention and ventilation conditions), and optionally cooperate with the fire protection system to automatically extinguish the fire. When the fire is extinguished, the smoke detector 15 stops alarming, and the control system automatically implements the corresponding process (tunnel post-disaster ventilation conditions). As a supplementary note, after the system automatically closes the fire shutter door 14, the fire door 16 can still be manually opened. Personnel will operate in accordance with relevant regulations to ensure that the fire door 16 is always closed to ensure the required function.

[0036] Preferably, the fireproof air duct 3 can ensure that the fire resistance limit of the air duct system meets 3 hours to better meet the system's smoke prevention and post-disaster ventilation functions. For example, the internal structure of the fireproof air duct system includes a finished fireproof air duct, an air valve used on the air duct, a non-combustible Class A rock wool insulation layer for wrapping the air valve components, a fireproof board and related fireproof support components.

[0037] In summary, the present invention is particularly applicable to small-section, long-distance tunnels located far from ventilation openings. Conventional mechanical smoke control systems and conventional mechanical ventilation systems are typically installed and operated separately. Conventional mechanical smoke control systems typically consist of air supply ducts with a fire resistance limit of no less than 1 hour, pressurized air supply fans, fire dampers, and pressurized air supply openings. Conventional mechanical ventilation systems are usually low-pressure or medium-pressure systems, with poor air duct sealing and high air leakage, making them difficult to meet the ventilation and smoke control needs of small-section, long-distance tunnel projects. The invention proposes a highly enclosed fire and smoke prevention ventilation system for long-distance underground tunnels, which can provide more lasting fire protection. By combining a mechanical smoke prevention system with a mechanical ventilation system, it can adapt to the ventilation needs of small-section, long-distance tunnel projects in normal times, smoke prevention and after disasters. Among them, due to its application in long-distance tunnels, the air flow in the deep tunnel is slow, and the flow of air is set to be pressure-driven. If no pressure is formed, the air flow is very slow, and the air quality deep in the tunnel cannot meet the requirements of long-term work of personnel inside. Considering that the rock walls inside the deeper tunnels may release gases such as radon, the air quality deep in the tunnel cannot be guaranteed without sufficient outdoor fresh air being supplied through pipes. In the event of a fire somewhere in the tunnel, the area can be separated from other areas, and positive pressure can be formed in other areas to prevent harmful smoke generated by the fire from entering other areas, thereby realizing smoke prevention function and providing protection for the safe evacuation of personnel. After the fire is extinguished, the pressure gradient can be used to gradually make the harmful gases flow to the exhaust outlet downstream of the air flow, so that the harmful gases are eventually replaced by fresh air.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; obviously, the embodiments described are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention; for ease of description, only the parts related to the relevant inventions are shown in the accompanying drawings. In the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other; modifying the technical solutions described in the aforementioned embodiments, or making equivalent replacements for some of the technical features therein, does not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fire and smoke prevention ventilation system for a long-distance underground tunnel, characterized in that: A tunnel (1) is provided, wherein the interior space of the tunnel (1) is divided into a plurality of adjacent fire compartments, wherein one or more fire compartments in the central portion of the tunnel (1) are special working areas (10), and the remaining fire compartments are tunnel separation areas; Fire walls are provided between the fire compartments and outside the outermost fire compartment. Openable and closable fire doors (16) and openable and closable fire vents (6) are provided on the fire compartments. A residual pressure valve (7) is also provided at the fire vents (6). The residual pressure valve (7) is only allowed to be opened in one direction and the allowed air flow direction is from the central part of the tunnel (1) to the outer part of the tunnel (1). An air inlet room (9) is connected to the outer portion of the tunnel (1), a fan (2) is provided in the air inlet room (9), an output end of the fan (2) is connected to a fireproof air duct (3), the fireproof air duct (3) branches to form a plurality of branch pipes and extends from the air inlet room (9) to each fireproof partition, a fresh air outlet (5) is provided at the end of each branch pipe of the fireproof air duct (3) in each fireproof partition, and a fire damper (8) for controlling on and off is provided on each branch pipe of the fireproof air duct (3).

2. The long-distance underground tunnel fire and smoke prevention ventilation system according to claim 1 is characterized in that: A regulating valve (13) is also provided in the branch pipe where the fresh air outlet (5) of the special working area (10) is located.

3. The long-distance underground tunnel fire and smoke prevention ventilation system according to claim 1 is characterized in that: Each fire compartment is equipped with a smoke detector (15).

4. The long-distance underground tunnel fire and smoke prevention ventilation system according to claim 1 is characterized in that: The fireproof air duct (3) is a fully welded structure.

5. The long-distance underground tunnel fire and smoke prevention ventilation system according to claim 1 is characterized in that: The air inlet room (9) is provided with an air inlet louver (12), and the input end of the fan (2) is connected to the outside world through the air inlet louver (12).

6. The long-distance underground tunnel fire and smoke prevention ventilation system according to claim 1, characterized in that: The fan (2) is a centrifugal fan unit composed of one or more centrifugal fans, and / or the fresh air outlet (5) is a single-layer louver air outlet.

7. The long-distance underground tunnel fire and smoke prevention ventilation system according to claim 1, characterized in that: The tunnel (1) is in a T-shape, a Y-shape, a straight line, a cross shape, a radial line shape, or a staggered network.

8. The long-distance underground tunnel fire and smoke prevention ventilation system according to any one of claims 1 to 7, characterized in that: Except for the fire wall adjacent to the special working area (10), other fire walls are also provided with fire shutter doors (14) that can be opened and closed.

9. The long-distance underground tunnel fire and smoke prevention ventilation system according to any one of claims 1 to 7, characterized in that: A smoke exhaust valve (4) is also provided in the branch pipe where the fresh air outlet (5) of the tunnel separation area is located.

10. A fire and smoke prevention ventilation method for a long-distance underground tunnel, characterized in that: It is implemented by using the long-distance underground tunnel fire and smoke prevention ventilation system according to any one of claims 1 to 7, wherein, in addition to the fire wall adjacent to the special working area (10), the other fire walls are also provided with openable and closable fire shutter doors (14), and a smoke exhaust valve (4) is also provided in the branch pipe where the fresh air outlet (5) of the tunnel separation area is located; The fire and smoke prevention ventilation method for long-distance underground tunnels includes three working modes, corresponding to the tunnel's normal ventilation conditions, tunnel fire and smoke prevention ventilation conditions, and tunnel post-disaster ventilation conditions; Under normal ventilation conditions in the tunnel, the fire door (16) is normally closed when not in use, the fire vent (6) is open, the fire shutter door (14) is open, the fire damper (8) is open, and the smoke exhaust valve (4) is closed; fresh air is sent into the special working area (10) through the fan (2) and the fire duct (3); the fresh air sent into the special working area (10) passes through the residual pressure valve (7) of the fire vent (6) and is pressed into the fire partition adjacent to the special working area (10); the fresh air then flows outward through the fire partitions one by one, and is finally discharged to the outside of the tunnel (1) through the fire vent (6) of the outermost fire partition; When a fire occurs in a certain fire compartment, the tunnel enters the fire smoke ventilation mode, the fire damper (8) corresponding to the fire compartment where the fire occurs is closed, the fire shutter door (14) and the fire vent (6) adjacent to the fire compartment where the fire occurs are closed, and the smoke exhaust valve (4) corresponding to the fire compartment where the fire does not occur is opened; fresh air is sent to the fire compartment where the fire does not occur through the fan (2) and the fire duct (3), and the fire compartment where the fire does not occur is ensured to be in a positive pressure state through the residual pressure valve (7) to prevent the smoke in the fire compartment where the fire occurs from entering the fire compartment where the fire does not occur; After the fire in the fire compartment where the fire occurred has been extinguished, the tunnel enters the post-disaster ventilation state, the fire damper (8) is opened, the smoke exhaust valve (4) corresponding to the fire compartment where the fire did not occur is closed, the smoke exhaust valve (4) corresponding to the fire compartment where the fire has been extinguished is opened, and the fire vent (6) is opened; fresh air is sent into the fire compartment where the fire has been extinguished through the fan (2) and the fire duct (3); based on the unidirectional conduction characteristic of the residual pressure valve (7), the smoke in the fire compartment where the fire has been extinguished gradually flows to the fire vent (6) downstream of the air flow due to the influence of the pressure gradient, and finally the smoke is discharged to the outside of the tunnel (1), and the fresh air fills each fire compartment.

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