In recent years, there have been frequent incidents of slab-rise building fires caused by external thermal insulation materials. On October 9, 2008, Harbin’s “360-degree latitude and longitude†Gemini Building Fire, February 9, 2009, Beijing CCTV Building’s new cultural center fire, April 19, 2009, Nanjing Central International Plaza Fire, September 9, 2010 Changchun Jiatai Dijing City Fire, November 15, 2010 Shanghai Jingan District Jiaozhou Road Teacher Apartment Fire, February 3, 2011 Shenyang Wanxin International A series of major fire accidents, such as building fires, have become important examples of public security firefighting forces dealing with fire protection of high-rise building exterior wall insulation materials. Therefore, studying the fire fighting technology of high-rise building exterior wall insulation materials is an increasingly faced and urgent problem for public security firefighting forces.
1 Fire characteristics of exterior insulation materials for high-rise buildings At present, domestic high-rise building exterior wall insulation materials systems generally use organic insulation materials such as EPS, XPS and PU. Organic materials have poor heat resistance and are easy to burn. In the event of a fire, a large amount of heat is released during combustion, and a large amount of toxic fumes are generated. In addition, the falling matter during combustion forms a new fire point, which is more likely to accelerate the spread of fire.
1.1 The burning speed is extremely fast. The fire insulation material of the high-rise building exterior wall is fired. Due to the sufficient air, it is greatly affected by the wind, and the fire spreads rapidly. Under normal circumstances, as the height of the high-rise buildings continues to increase, the wind speed outside the building also increases, and the relationship is directly proportional. For example, the wind speed is 5 mA from the ground lm. Under the same conditions, the wind speed can reach 15m/s at a height of 90m, and the wind speed can reach 30m/s at a temperature of 200~300m. The wind direction is uncertain due to the continuous increase of wind speed. It directly leads to the difference in temperature and pressure between the upper and lower layers of the building, thus forming a fire pressure. This increases the extraction force of the flue gas and the amount of air required for combustion. The result is that the fire borrows the wind, and the wind helps the fire, intertwined, thereby affecting the speed and direction of the fire. Especially after the fire of the high-rise building exterior wall insulation material, the fire spreads particularly rapidly due to the smoke effect, and it is easy to form a three-dimensional fire. For example, in the fire of Nanjing Central International Plaza, the building is 50 stories high and has a twist of 187m. The fire point is an 8-story podium platform. After 12 minutes of fire, it has spread to 18 floors. After 22 minutes, the open flame spread to the top of the building. The fire was attached to the cultural center attached to the new site of the CCTV Building in Beijing. The building has 30 floors above ground and is 159m high. After a fire of lOmin, a three-dimensional fire has been formed. The fire in the Jiaozhou Road teacher apartment in Jing'an District, Shanghai, is 28 stories high and 85m high. The entire building has formed a comprehensive, three-dimensional combustion in less than 7min.
1.2 After the external and internal horizontal spread of the high-rise building exterior wall insulation material caught fire, the building facade quickly burned and spread. Although the window glass theoretically melts around 725~900. However, under fire conditions, due to various factors such as uneven heating and expansion deformation of the glass, and a large temperature difference between the inner and outer surfaces, it is generally cracked and broken at about 250T. Through the open window of the broken glass, the fire quickly ignites the combustibles in the room, and the multiple fire points spread horizontally to the interior, forming a full-scale three-dimensional combustion inside the building, breaking the routine of one-bedroom and one-bedroom development of the fire in the building. No obvious fire development. Stage division. For example, in the fire of Nanjing Central International Plaza, the two fire pillars formed, causing the wall of the two adjacent air conditioners to install the groove (shaft) from the 7th floor to the top of the top floor to overfire (the east side 7th floor to the top floor, west side) The 7th to 41st floor was over fired and spread horizontally indoors.
1.3 High-temperature thick smoke in the building The external wall insulation material mainly uses 篼 molecular organic materials. After burning organic materials, a large amount of toxic gases will be produced. Once the fire spreads, the high-rise buildings are surrounded by the sea of ​​fire. High-temperature smoke gathers in the building, which seriously threatens the safety of trapped people in the building and hinders firefighters from carrying out personnel search and fire fighting. Shanghai killed 58 people and injured more than 70 people. In the implementation of the firefighters in the implementation of firefighting, the fighting action is extremely difficult due to the accumulation of a large amount of high-temperature smoke in the building.
1.4 burning falling objects easily form flying fire high-rise building exterior wall insulation material burning is prone to hot melt shrinkage, causing shedding. In the process of falling, the burning object is affected by the wind, forming a flying fire, causing multiple fire points. The distance of the flying fire is related to the size of the falling object and the wind, some meters, some tens of meters or even more. For example, in Shenyang Wanxin International Building, after all the external walls of Block B are on fire, the adjacent Block A is burned by the burning of the burning materials, and the outer wall of the south side burns and spreads through the window to the 30-story and 42-story rooms. Nanjing Central International Plaza, a fire truck parked more than ten meters away from the building, fell due to the burning insulation material, paste on the top of the fire truck to cause burning.
2 High-rise building exterior wall insulation material fire-fighting technology 2.1 centralized dispatch, the first time rushed to the scene to save the high-rise building exterior wall insulation material fire, fire fighting power scheduling should be accurate and timely, starting from the first battle. Therefore, it is necessary to strengthen the first outing, and concentrate on investing fire-fighting forces in time to timely control the fire and save lives, so as to grasp the initiative of fire fighting. For example, in the fire of Nanjing Central International Plaza, 37 fire engines and 194 officers and men from 10 squadrons and the Combat Support Brigade were rushed to the scene. The fire in the cultural center attached to the new site of the CCTV Building in Beijing, the first time, 15 squadrons, 46 fire engines and hundreds of officers and men were rushed to the scene. In the fire of the teacher apartment in Jiaozhou Road, Jing'an District, Shanghai, five fire squadrons and one special squadron, 15 fire engines and 130 fire officers and soldiers were rushed to the scene. Shenyang Wanxin International Building fire, Shenyang Public Security Fire Brigade mobilized 27 fire squadrons, 5 enterprises and professional full-time team of 108 fire engines, 702 officers and men rushed to the scene.
2.2 Fast ascent, control fire vertical wraps High-rise building exterior wall insulation materials fire spread rapidly, public security firefighters must be fast and fast, in order to effectively control the fire. After the public security firefighting troops arrived, they used fire elevators to transport personnel and equipment to the top of the building, using indoor fire hydrants, and blocking the outer wall fire. For example, the fire in Nanjing Central International Plaza can be successfully extinguished within one hour, and all trapped personnel can be rescued. In addition to the firefighters fighting for rescue, one of the important factors is that after the fire brigade arrives, it is fast and fast, using fire elevators. Quickly climb to the 50th floor, use the indoor fire hydrant to lay the water belt to the top of the building, and conversely suppress the upward spread of the fire, which plays a key role in preventing the expansion of the fire. 2.3 Controlling the lower defense, after suppressing the fire from the outside, the high-rise building exterior wall insulation material burns extremely fast, the fire will spread rapidly along the outer wall longitudinally and horizontally, and the burning combustibles will fall, which will cause a new fire. In the deployment of power, it is necessary to use the lift truck to fully suppress the fire. At the same time, set the water gun position on or around the podium platform of the high-rise building to extinguish the falling combustibles in time to block the way the fire spreads. For example, in the fire of Nanjing Central International Plaza, three lift trucks were used to suppress the fire from the outside, and a water gun position was set on the 9-story platform to extinguish the falling flame; the Beijing CCTV building was attached to the cultural center fire, using 6 lifts from the outside. Suppressing the fire; in the fire of the teacher apartment in Jiaozhou Road, Jing'an District, Shanghai, 14 lift trucks were used to suppress and strike the fire from the outside; in the fire of Shenyang Wanxin International Building, three fire trucks were organized on the south side of Block B to force the fire to be suppressed. On the west side of Block A, six high-rise fire trucks were organized to suppress the external wall fire. Two water gun positions were placed on the podium platform to extinguish the falling combustibles.
2.4 Comprehensive search and rescue, timely evacuation of trapped personnel high-rise buildings in many states with the characteristics of personnel gathering, so after the fire commander arrived at the high-rise building fire scene, we must conscientiously implement the "rescue first" guiding ideology, take various measures Rescue or protect the lives of people. Immediately after the fire brigade arrived, a special person was dispatched to the fire control room to promptly launch emergency broadcasts and emergency lighting to guide the trapped people to evacuate. The fire elevators were used to rescue the trapped people who were seriously threatened by the fire, and the smoke exhaust system inside the building was quickly opened. Provide air and smoke, reduce the hazard and impact of smoke, provide favorable conditions for the rescue of firefighting, and use the video surveillance system to grasp the situation in real time, inform the unit to call the room to inform the passengers to evacuate; at the same time, make a number of rescue groups to search for help. The trapped person, to identify the searched room, to make sure that there is no omission, to ensure that all internal personnel are evacuated. The commander also proceeded from the most unfavorable situation of fire development according to the scene danger, and pre-judgment in advance, and decisively sent a rescue team to evacuate the adjacent buildings threatened by the fire, to ensure that no one was killed or injured at the scene of the fire. For example, in the fire of Shenyang Wanxin International Building, the Shenyang detachment immediately formed 18 rescue groups to search and rescue the trapped people. In the first time, they searched for 60 people in the fire, and guided the evacuation of people in the nearby Block A. 210 people. After the fire on the south side of Block A, the on-site command immediately ordered all search and rescue teams to search Block A again to ensure that all internal personnel were evacuated.
2.5 Internal attack melee, layer-to-wall interception to the interior of the slab building exterior wall insulation material fire, in addition to rapid upward and downward spread, the fire will spread along the floor connected to the external wall to the floor, it is easy to form a three-dimensional fire inside and outside. Therefore, after the first force arrives, set up multiple combat groups, internal storms to extinguish fires, and tactical measures to eliminate the layers. Fire fighting from the periphery is mainly limited by the equipment's temperature limit, and the flame position is high. It is difficult to spray the fire extinguishing agent directly onto the flame, and the fire extinguishing effect is not achieved. Therefore, for high-rise building fires, combatants must be programmed to fight. The combat teams make full use of internal stairs, fire elevators to enter the interior of the building, use indoor fire hydrants, implement internal attack melee, control and extinguish fires. For example, in the fire of Shenyang Wanxin International Building, the on-site command department organized 77 fire-fighting and rescue teams to carry out internal attacks inside the two buildings in Block B and Block A, effectively preventing the spread of fire and preventing further expansion of the disaster.
2.6 Various measures to ensure effective water supply in the fire. Fully utilizing the fixed fire-fighting facilities of the first-floor buildings for fire-fighting is an effective way to quickly extinguish fires. After a fire, the firefighting force that arrives in advance should make full use of the internal fire-fighting facilities and supply water to the building through the fire truck connected to the water pump adapter. When the indoor fixed fire-fighting facilities cannot meet the fire-fighting needs or lose their functions, they should be quickly supplied to the fire site through the fire truck to ensure that the water supply to the fire farm is uninterrupted. In the case of a large burning area and a large number of internal fire points, the working sprinkler system should be immediately shut down to ensure the use of the wall fire hydrant.
If the fire water consumption of the fire farm is large, the municipal fire hydrant pressure is not enough. There are high-rise buildings or public buildings near the fire building, and water supply can be implemented using the adjacent unit water source. This method of water supply is to pump water from a fire-fighting water pump in a high-rise building or a public building adjacent to a fire unit, and to lay a water belt to supply water to an outdoor fire truck. According to the urban fire protection design, the underground water pool of the raft building is in the hundreds of tons, and the water supply can reach thousands of tons, while the water supply of the fire pump is 30~40L/S, which is equivalent to the water consumption of 3~4 municipal fire hydrants. . If you can make more use of several adjacent slab buildings, you can ensure that there is sufficient and constant pressure fire water in the fire to ensure uninterrupted water supply.
In the choice of fire extinguishing agent, compressed air foam has the advantages of high fire extinguishing efficiency, strong fire control ability, fast foaming speed, light weight, easy laying and moving water belt, etc., which can be used for vertical laying of water belt and pressure supply. Fired a gun to win the time. Compressed air foam is like a layer of felt, which is easy to adhere to the pre-vertical façade. It has strong fire extinguishing and protection performance, and greatly reduces the pressure of water supply behind the fire. Therefore, in the actual combat, these cockroach performance fire extinguishing agents should be given priority. The fire layer lays a solid foundation for the successful suppression of the fire.
2.7 Searching layer by layer, destroying the residual fire After the fire in the high-rise building is basically extinguished, the combat sections should be redeployed, and the search task should be assigned to each squadron, respectively, to the rooms, elevator shafts, and pipeline wells on each floor of the building. Repeated carpet search on other parts to ensure that no dead angles are left, and the flammable materials accumulated in the room are cleaned to prevent re-ignition.
Concluding remarks: The fire of the outer wall insulation material of the raft building is a new topic raised by our firefighting work under the current fire situation. All the officers and men of the public security firefighting team must constantly explore the development characteristics and fire-fighting technology of the bunker building fire. It has the equipment to exert the best performance of fire extinguishing and win the fire fighting of the fire of the external wall insulation materials of high-rise buildings under modern conditions, and play a proper role for the resident side.
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