Analysis on fire characteristics and fire safety c

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Analysis on fire characteristics and fire safety countermeasures of cultural relics and ancient buildings

cultural relics and ancient buildings are an important part of the precious 5000 year historical and cultural heritage of the Chinese nation, a historical witness of the long history of Chinese civilization, and a non renewable human resource. Therefore, the protection of these cultural relics and ancient buildings will benefit this world and contribute to the future. Among all the hazards to cultural relics and ancient buildings, fire is undoubtedly the first to bear the brunt. The data shows that in 2000, there were 6 Fires in cultural and Museum units and ancient buildings across the country, burning one city tower, one archway and five ancient buildings. In 2001, four fires broke out in cultural and Museum units and ancient buildings across the country, burning a hall and 165 square meters of ancient buildings. In 2002, there were 4 fires in cultural and Museum units and ancient buildings across the country, burning a temple, a main hall and 65 houses, covering an area of 1865 square meters. Recently, fire accidents of cultural relics and ancient buildings have occurred frequently, which makes people feel distressed. For example, on January 20, 2003, a fire broke out in Wudang Mountain, a world heritage site, and the main hall of the Millennium famous Yuzhen palace was reduced to ashes; On June 20, 2004, a fire broke out in the Huguo temple in Beijing, which has a history of more than 700 years, and its west side hall was completely burnt down. Therefore, at present, the fire situation of cultural relics and ancient buildings in China is very serious, and the fire safety of cultural relics and ancient buildings has become the top priority of the tasks of fire departments at all levels

based on the basic principles of fire science, this paper will analyze and discuss the fire risk and fire dynamic evolution process of ancient buildings, and provide some reasonable suggestions on the fire safety countermeasures of ancient cultural relics

2. Fire risk of ancient buildings

the reason why many ancient buildings in China's history were destroyed by fire, and the vast majority of ancient buildings that survived today have also experienced fire disasters, is that these ancient buildings themselves have a great fire risk

(I) large fire load and low fire resistance rating

the vast majority of ancient buildings in China take wood as the main material and wood frame as the main structural form. The fire load is far higher than the fire load specified in the current national standards, with great fire risk and low fire resistance rating. After years of drying, the wood in ancient buildings has become "all dry wood". The water content is very low, so the list of enterprises that meet the standard conditions is published, so it is very easy to burn, especially some decayed wood, because of its loose texture, it will catch fire even when encountering Mars in the dry season.

various wood components in ancient buildings have good conditions for burning and spreading flames. After the ancient building is on fire, it is like a light steel keel gb/t 11981 (2) 001 furnace full of dry firewood, and the roof is tight, which will lead to the smoke and heat inside the roof are not easy to emit, the temperature will accumulate rapidly, and quickly reach "flashover" in case of fire. The beams, columns, rafters and other components of ancient buildings have a large surface area, there are many cracks in wood and spliced cracks, and most of the ventilation conditions are relatively good. Some ancient buildings are built on the top of mountains. After a fire, the fire spreads quickly and burns violently, which is very easy to form three-dimensional combustion.

(II) there is no fire separation, which is prone to "fire and camp"

most ancient buildings in China are based on a variety of single buildings, forming various courtyards. In the courtyard layout, the form of "quadrangle courtyard" and "Gallery courtyard" is basically adopted. Both of these two layout forms lack fire separation and safe space. If one of them is on fire and cannot be effectively controlled at the moment, it will "catch fire at the city gate and bring disaster to the pond and fish", and the adjacent wood structure buildings will soon burn in a large area, forming a situation of "fire burning the camp".

(III) the lack of fire-fighting facilities makes it difficult to fight fires.

ancient buildings in China are distributed all over the country, and most of them are far away from cities and towns, built in high mountains and deep valleys with quiet environment. These ancient buildings generally lack the ability of self-defense and self rescue, and there are not enough trained full-time firefighters, nor are they equipped with and installed with effective fire-fighting facilities. In case of a fire, the fire brigade in the town is beyond its reach, and only let it burn until it is finished. Most ancient buildings lack fire water sources, and some tall ancient buildings are even more difficult to attack. In addition, the roads around ancient buildings are mostly narrow, and some are also equipped with thresholds and steps, so fire engines cannot pass at all, which brings great difficulties to the fire fighting work

(IV) the management and use of ancient buildings are poor, and the problems are complex.

the division of labor and responsibilities of the competent departments of some ancient buildings are not clear, and fire safety management is often ignored in order to pursue economic interests. In the use of ancient buildings, some places use ancient buildings to set up hotels, restaurants, guest houses, factories, warehouses, etc. the fire source management is not strict, the wires are pulled and connected randomly, and the line switches are set up randomly. A large number of shops have been opened around some ancient buildings, and fire risk factors have increased significantly. These fire safety problems in management and use also pose a serious threat to the fire safety of ancient buildings

3. The dynamic evolution process of ancient building fire is a process with complex essence. Its gestation, occurrence and development include turbulent flow, phase change, heat and mass transfer, complex chemical reactions and other physical and chemical interactions. It is a three-dimensional, multiphase, multi-scale, unsteady, non-linear The unbalanced driving force breaks the technological monopoly process of developed countries such as Europe and Japan; The dynamic process also interacts with external factors such as people, materials, environment and other intervention factors. Therefore, analyzing the evolution process of fire dynamics is not only helpful to deepen our understanding of the fire of cultural relics and ancient buildings, but also provides scientific guidance for further targeted formulation of accurate and reasonable fire safety countermeasures

the whole fire process of ancient buildings can be roughly divided into four stages: fire, initial growth, full combustion and weakening. As shown in Figure 1 below


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