In order to alleviate the worsening urban traffic problems at present and in the future, some big cities in China have built or are in the process of building subways. At present, Beijing, Tianjin, Shanghai and Guangzhou have been put into operation, and Nanjing and Shenzhen are under construction. Subway will become the main means of transportation in major cities in China. This paper mainly introduces the fire-fighting facilities of subways built and under construction in China, and analyzes the main problems existing in subway fire-fighting in China.
1 Main fire-fighting facilities in China's subway
1. 1 Guangzhou Metro
1. 1. 1 four sets of communication equipment ensure the smooth flow of fire information.
Guangzhou Metro can quickly collect relevant information from four channels. First, the automatic alarm system, the FAS automatic fire alarm system in the station is very sensitive, which can automatically collect fire information within the jurisdiction and quickly transmit it to the station control room and control center, and automatically trigger the fire smoke exhaust mode; Second, radio communication, station staff and subway drivers can transmit accident information to the control center through the wireless system; Third, wired communication emergency telephone, staff can contact the control center through wired telephone; The fourth is the CCTV video transmission system in the platform. An omni-directional monitor is installed in the station to collect all video information in real time.
1. 1.2 building decoration refractories
Guangzhou Metro train seats are made of stainless steel, the optical cables in subway tunnels are made of fire-resistant and flame-retardant low-smoke halogen-free materials, the decorative materials of trains and stations are made of non-toxic and non-combustible materials, and the station section works are made of reinforced concrete structures. These designs reduce the possibility of fire in the station itself to the lowest point.
1. 1.3 Perfect fire control facilities.
Each carriage on the train is equipped with two fire extinguishers, which is enough to deal with the initial fire in the carriage. The fire fighting facilities in the station are perfect, and sufficient fire hydrants and extinguishers are equipped according to the specifications. Automatic gas fire extinguishing system shall be set in the important equipment room. Fire hydrants connected with external fire engines are set near the entrance and exit of the station to facilitate the support of external rescue forces.
1. 1.4 The control system is reliable.
There is an emergency alarm button on the train. In case of fire, explosion and other accidents, passengers can quickly press this button to inform the driver. When handling the accident, the driver will drive the train to the front station as far as possible, so as to rely on the fire fighting power of the station for disaster relief (it usually takes about 1.5 minutes for the train to travel to the next station). If the train has entered the station, passengers can pull the red emergency mechanical unlocking handle above the door and the green unlocking button on the screen door to open the door for evacuation (even if there is no power supply, the train door and screen door can be manually opened), so that passengers can't open the door like the Korean subway accident.
In case of fire, explosion and other accidents, the driver will inform passengers to evacuate through the emergency evacuation doors at both ends of the train, and at the same time start the emergency lighting and ventilation system in the car (the emergency standby power supply in the car can guarantee the lighting and air supply in the car for 45 minutes). Passengers can evacuate in the direction of fresh air under the organization of the staff.
Guangzhou Metro has a high degree of automation. When the train in the station caught fire, the smoke sensing system quickly transmitted the information to the control center, and started the signal blocking system to prevent the adjacent trains from entering the station. At the same time, each station also has the function of car deduction, which is simple to operate. Guangzhou subway station has reliable smoke exhaust facilities, and its smoke exhaust capacity is far greater than that of toxic gas produced by fire. In the design of smoke exhaust, according to the principle of "people-oriented", the system can collect fire information within 2 seconds and start the equipment within 2 minutes. After the smoke exhaust equipment is started, a large amount of fresh air flows in from the entrance and exit. Through reasonable airflow organization, the smoke is discharged from the ventilation shafts at both ends of the station to ensure that passengers can always evacuate against the fresh air.
1. 1.5 dual power supply system to ensure foolproof.
The equipment for providing important fire information and smoke exhaust in Guangzhou Metro adopts the first-class load, which is a "double power supply and double circuit", and the facilities at both ends of the station are also set up independently for mutual backup. When one power supply loses power, the other power supply is automatically put into power supply immediately to ensure the reliable operation of smoke exhaust equipment. Even if the double circuit power supply is completely interrupted, the station emergency power supply can still provide basic electricity for 1h, such as guiding signs and emergency lighting, to ensure foolproof.
1. 1.6 Strict management system.
Guangzhou Metro has a strict management system, which can effectively prevent and control fires. Guangzhou Metro staff will start to check the smoke exhaust equipment before operation every day to ensure the normal operation of the equipment. The company conducts paramilitary management of employees and conducts corresponding fire drills regularly. Employees are proficient in all kinds of emergency handling skills, and have formulated a set of perfect accident emergency handling scheme in operation practice.
1.2 Shanghai Metro
Shanghai subway has two sets of automatic fire prevention facilities: two-level automatic monitoring system, one in the station and one in the central control room; Automatic fire extinguishing and spraying systems, including water spraying and air spraying, can be adjusted according to different fire causes. There are fire hydrants, emergency lighting and alarm telephones in the tunnel. In the carriage of subway train, the bracket of fire extinguisher on board was reformed, 256 sets of fire extinguishing equipment were added, and luminous indication signs were set up at eye-catching positions in the carriage to indicate the way of passage, which was convenient for passengers to use in emergency.
178 sets of gas masks have been distributed to 23 underground stations, and there are also special smoke exhaust devices in subway tunnels. In case of fire, the emergency fan system in the tunnel will be started in the shortest time to discharge toxic smoke and prevent suffocation. In addition, if there is an accident in the train compartment and the door cannot be opened, you can manually open the special "escape door" in front of the train to evacuate the passenger flow. Emergency lights, evacuation signs and safety prohibition signs are set up in underground stations.
1.3 Shenzhen Metro
1.3. 1 decorative materials
All vehicles and stations in Shenzhen Metro adopt fire-proof materials certified by the Fire Bureau, and the materials such as carriages, handrails, seats, equipment pipes, platforms, walls and ceilings of vehicles are non-combustible or flame-retardant materials.
1.3.2 automatic control and fire alarm system
The automatic control system and fire alarm system of Shenzhen Metro are the most advanced in the world. When an emergency happens, the alarm system can give an alarm reliably, accurately and quickly within a few seconds. After receiving the alarm signal, the automatic control system will automatically turn on and operate various emergency rescue equipment such as fans, water pumps, emergency lighting and gas fire extinguishing devices. If the circuit is interrupted, the battery will start the rescue equipment above, so there will be no situation that the door cannot be opened.
1.3.3 Smoke control and exhaust design
The station is designed with fire prevention and smoke prevention zoning system. There are several smoke storage areas on the ceiling of the station, and each smoke storage area is equipped with a smoke exhaust duct, which can quickly draw smoke and toxic gases in and out to prevent the spread of fireworks.
1.3.4 emergency evacuation system
The emergency evacuation system of Shenzhen Metro is perfect. In case of fire, all gates and doors will automatically open to a safe position, all elevators will run in the same direction, and the evacuation passage is spacious, which can ensure that all passengers and staff can evacuate to a safe position within 6 minutes in case of emergency. At the same time, Shenzhen Metro is designed to use a software management system to prevent emergency fires. In the design, the possible fire situations of all stations and carriages are simulated into 100 kinds of fire situations and input into the computer system, and the computer system quickly starts the fire emergency evacuation system according to the actual situation.
1.3.5 fire water supply system
The fire hydrant system of Shenzhen metro is a wet system, and the pipe network is arranged in a ring shape. Its service scope covers the lowest slope of the station and the adjacent area of the station (at the connecting passage). Fire pipes are connected from urban water pipes and arranged in the lower part of the station hall and platform floor, as well as in sections and pedestrian walkways, and fire branch pipes are set according to the location of fire hydrants. Fire hydrant box spacing: the platform floor of 30m ~ 40m of the station hall floor is 40m ~ 50m, and the equipment area and pedestrian passage of the station hall floor and platform floor are set as required.
A fire pump adapter is set on the water supply inlet pipe outside the station, and an outdoor low-pressure fire hydrant is set within 40m of the adapter.
1.4 Beijing subway
Beijing is the first city in China to build a subway. At that time, the first-line subway in Beijing was not built for the development of urban traffic, but for preparing for the international environment at that time. Therefore, its internal structure and design standards are far from meeting the current use requirements. The building structure of Beijing subway adopts reinforced concrete structure, and the first-line subway is equipped with a fire hydrant every 100m, and the second-line subway is equipped with a fire hydrant every 300 m ~ 500 m The machine room is equipped with automatic fire extinguishing system, and all stations are equipped with portable fire extinguishers. Smoke prevention, ventilation and normal ventilation share a system. The station is equipped with emergency lighting and the train is equipped with emergency broadcasting.
2 China subway fire problem
2. 1 There are many fire hazards in the old subway.
2. 1. 1 There are serious hidden dangers in electrical equipment.
There are more than 50 substations in Beijing Metro Lines 1 and 2. Except for a few on the ground, the others are located at stations along the subway. In addition to power generation equipment, there are six 35kV substations in the underground power station, which adopt oil-immersed transformers and oil-immersed arc suppression coils. Once the power station transformer or arc suppression coil explodes and catches fire, oil will leak everywhere and flow into the subway tunnel from the hoisting port or cable hole, which will directly endanger the safety of running vehicles and spread the fire. In addition, there is no fireproof partition between the lifting port of the distribution room and the tunnel, which makes the fire spread more easily.
2. 1.2 Incorrect laying of wires and cables
On the cable supports on the walls of some tunnels in Beijing subway, cables of various voltage levels are mixed together. As long as one wire catches fire, it will inevitably cause a power outage accident of the whole system and expand the scope of the accident. In addition, some unprotected cables are directly laid behind the protective plate of the contact rail, or some are soaked in water, and even some cable heads are directly buried in cement without treatment. Most of these cables are made of PVC without flame retardant treatment. In case of fire or short circuit, a large amount of smoke and toxic gas will be generated, which will seriously endanger the lives of passengers and emergency personnel. In addition, underground rats are seriously damaged, and there have been many accidents in which rats bite wires, resulting in short circuit of cables and burning of equipment.
2. 1.3 The fire load is large.
There are 28 stations and 227 commercial service outlets in Beijing Metro 1 Line 2, and more than 4000 advertising carriers 14000 are installed in the station halls, platform halls, aisles and carriages of each line. These facilities not only occupy the limited evacuation space, but also increase the fire load in the subway station and increase the possibility of fire.
2. 1.4 Equipment is overloaded.
Exhaust fan, air conditioner, escalator, communication signal controller, lighting equipment and other electrical equipment. Beijing subway is prone to fire under long-term overload operation.
2. 1.5 building a house without permission
Most of the buildings in Beijing subway are nonflammable, but a considerable amount of combustible materials are used in the decoration of halls and rooms. Some important computer rooms, equipment rooms and duty rooms use wood floors, parapets, ceilings and plastic foam sound-absorbing materials. Some temporary rooms have also been built in the underground workshop to ensure the living needs of the staff. At the same time, subway workers use a large number of dehumidifiers, electric heaters, electric furnaces and other electrical equipment to pull wires privately, which increases the fire risk.
2. 1.6 The safety performance of electric buses is not high.
There are 1 17 trains and 579 electric buses in Beijing subway, all made of FRP. However, as China has not formulated the detailed rules for fire protection rating of subway vehicles, the design of electric buses can only refer to the existing fire protection technical standards, which are not completely suitable for the special requirements of subway vehicles, and the flame retardant performance of interior materials is not high. In addition, the alarm communication device in the car is different from the door opening device in the accident state, which is not convenient for passengers and drivers to report the disaster or take corresponding measures.
2. 1.7 Incomplete fire control facilities
The fire fighting equipment of Beijing Metro 1 Line and Line 2 is very simple. There is no automatic fire alarm system and automatic fire extinguishing facilities in the platform and station hall. Although the subway station has a fire hydrant system, it is not well maintained. The fire fighting pipe network of subway in some stations is not connected with the municipal pipe network, and some fire hydrants are corroded and cannot be used. Evacuation signs in subway tunnels do not meet the requirements of "one for interval tunnels and evacuation passages every 100 m" and "the height of evacuation signs from the ground is 1m ~ 1.2m"; Emergency lighting did not meet the requirement of "every 20m or so in evacuation passages and interval tunnels".
2. 1.8 poor ventilation and smoke exhaust facilities
Each line in Beijing has 1 14 ventilation and smoke exhaust machines. When a fire accident occurs, the normal exhaust system can be changed to smoke exhaust system, but the normal temperature of the fan is limited to 80℃, which does not have the ability to exhaust smoke quickly in a short time. In addition, there is no smoke-proof hanging wall at the stairs of the platform and platform hall, and there is no fire-proof and smoke-proof area.
The wind pavilion of Beijing subway is seriously occupied and blocked, which also causes certain harm. There are 95 ground wind pavilions on Metro Lines 1 and 2, some of which are closed and some of which are partially blocked, which can not guarantee the effective operation under high temperature and heavy smoke, and it is bound to cause great difficulties for safe evacuation and fire fighting and rescue.
2. 1.9 The safety evacuation capability is seriously insufficient.
The original designed daily passenger volume of Beijing Metro is 300,000, but now the maximum daily passenger volume has reached more than 2 million, and the peak hour is 24,000. The maximum number of stops during peak hours can reach 458 1 passenger, which seriously exceeds the design capacity. Beijing subway is designed with 265,438+05 entrances and exits. The width of exit stairs and evacuation passages in most subway stations can not reach the ability of "evacuating a train of passengers and passengers and staff waiting at the platform within 6 minutes in case of fire", and the rapid growth of passenger flow is underestimated. In particular, there are only two exits in several stations in the west of the first line. Once a fire breaks out, the evacuation capacity is obviously insufficient. Moreover, the walking distance of some platform evacuation passages is long, which seriously affects the evacuation speed.
2.2 The safety design of the equipment area is unreasonable.
There are many lounges, offices and other non-working places in Beijing subway, and its safety evacuation design can not meet the requirements in terms of the number of exits and safe distance. There is no safe exit in the equipment area of Shanghai subway, so the evacuation of its staff has become a major hidden danger. Because the equipment rooms are small and messy, the use functions and fire-fighting properties of various houses are very different, and the management of various internal systems is complicated, so the fire safety design is very difficult. Take a station of Guangzhou Metro as an example, there is a ventilation and air conditioning duct system with the size of 1 1 in only one equipment management room area, as well as numerous power cable trays, communication cable trays and various large-diameter water pipes. Due to functional requirements, each system is often staggered. It is quite difficult to arrange these systems reasonably in a limited space, and how to do a good job in fire safety design is a problem worthy of attention.
2.3 It is difficult to grasp the design of smoke control and exhaust in subway stations.
The subway station is a very special building. There is no reliable theoretical support on whether or not to divide smoke prevention zones, where to divide smoke prevention zones, and how to rely on organized airflow control and sufficient exhaust volume to ensure the requirements of smoke exhaust.
3. Some suggestions on subway fire protection design in China.
In view of the above-mentioned problems existing in China's subway, it is believed that improvements can be made in the following aspects.
3. 1 subway car
(1) The subway car should be made of incombustible materials and meet the requirements of low smoke, non-toxicity, high temperature resistance and easy cleaning. In addition, the car should be equipped with a backup power supply. In case of fire and power failure, it is necessary to ensure a considerable lighting brightness. At the same time, the automatic sliding door can be automatically opened in case of power failure, which is beneficial to personnel evacuation.
(2) Communication equipment should be installed in the carriage to facilitate passengers and drivers to report the disaster in case of fire; Install a broadcast system to inform passengers of the fire location and evacuation direction in case of fire.
3.2 Safe evacuation
(1) For the safety evacuation design of subway stations with annex buildings, the width of the total safety exit must ensure that subway passengers, staff, customers and sales personnel in the commercial service building can be evacuated within 6 minutes in case of fire. In addition, for stations like Beijing Xidan Station, where the second floor is a commercial service outlet and the third floor is a subway platform, there should be at least two exits directly to the ground on the third floor subway platform to facilitate evacuation.
(2) The commercial advertisements and service facilities that have been set up should be strictly examined, and those that affect the safe evacuation should be resolutely dismantled to ensure the safety of evacuation.
(3) In subway stations, corridors and other places with frequent passenger flow, or where it is difficult to set up firewalls or fire doors outside the use area of fire zones, fire shutters can be used instead of firewalls or fire doors, and fire shutters should have the function of delaying descent or setting small doors.
(4) There should be at least one entrance and exit in the station for the barrier-free design of disabled people and women and children passengers. In design, according to the possibility of specific terrain, it can be designed as a ramp, a moving sidewalk with a small slope or a vertical elevator that goes straight to the platform. The width of barrier-free ramp shall not be less than 1.60m, and the slope shall not be greater than 8%.
3.3 Subway Smoke Exhaust
Carry out the smoke control experiment and fire simulation of the subway as soon as possible, and theoretically give the ventilation mode that conforms to the operation of fire accidents, so as to form a better airflow pattern in case of fire and create conditions for people to escape.
3.4 Automatic alarm system
Detectors that can detect more than two environmental parameters must be used in subway tunnels to prevent false alarms. At the same time, with the change of acquisition parameters with time, the parameter value of "pre-alarm/alarm" should be set. Only by comprehensively processing and analyzing various parameters can the controller software send out accurate alarm signals.
3.5 important equipment room
(1) For important equipment rooms such as control room, power distribution room and air conditioning room, effective fire prevention measures should be taken for isolation. It is necessary to consider not only the heat dissipation and ventilation of the machine at ordinary times, but also the absolute safety of the space in case of fire. Therefore, the doors or windows of these important computer rooms can be replaced by fire doors or windows with vents, which can be ventilated at ordinary times and closed in case of fire.
(2) For some unnecessary temporary underground production and living houses, appropriate demolition can be carried out. At the same time, further establish and improve the fire safety management system, clarify the fire safety responsibilities of personnel at all levels, popularize the knowledge of fire fighting and evacuation, strengthen the inspection of fire control facilities, maintain them regularly, supplement personal protective equipment and increase emergency rescue equipment.
(3) Metro maintenance materials and their warehouses should be located on the ground alone.
3.6 Establish a safety inspection system
Security inspection system should be added at the exit of subway platform, especially in large stations where crowds gather. Setting up a safety inspection system can prevent some passengers from carrying flammable and explosive materials into the station to avoid increasing fire hazards.
4 conclusion
Through the above analysis, the fire safety design of China's subway should be controlled from the following aspects: the division of fire protection zones, the non-combustible treatment of decoration materials, the setting of fire alarm system and automatic fire extinguishing system, smoke control facilities, evacuation signs and emergency lighting. At the same time, we should correctly handle the relationship between operation and safety, rational design and economic development. On this basis, establish a scientific fire prevention management system, improve the safety quality of firefighters in subway enterprises, and establish a subway fire fighting and rescue mechanism with unified command, efficient operation and clear division of labor; Increase investment, strengthen equipment, do a good job in fire fighting and rescue work, and nip in the bud.
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