火灾场景中水幕对玻璃破裂行为影响的实验研究

发布时间：2018-04-25 02:05

本文选题：火灾 + 玻璃　；参考：《中国科学技术大学》2015年硕士论文

【摘要】：出于美观、经济、透明性好等原因,玻璃在现代建筑中的应用越来越广泛,玻璃的种类也越来越多样化。但是当火灾发生时,玻璃幕墙或玻璃窗结构却是建筑中最薄弱的环节,很容易破裂脱落形成新的通风口。而一旦形成新的通风口势必会加剧火势蔓延,影响人员疏散,造成更大的生命和财产损失。为延长玻璃在火灾中的防火时间,建筑中一般会配备相应的喷淋或水幕设施,用于火灾发生时降低玻璃温度。国内外学者已经对普通玻璃、钢化玻璃、防火玻璃等的水保护效果进行了一定的研究,并得出了一些定性结论。本文在大量调研国内外文献的基础上对水幕对玻璃破裂行为的影响进行了大量的实验研究和分析。本文根据实验目的和方案设计并加工了由供水系统、水幕喷淋系统、火源模拟系统、测量控制系统及水幕回收系统等组成的实验装置。本文实验部分对钢化玻璃和非钢化Low-E、浮法玻璃三种应用最广泛的玻璃进行了研究。实验中将玻璃试样加热至不同温度然后实验人员手动开启水幕,模拟研究水幕在火灾不同阶段开启时玻璃的破裂脱落行为。文中也对施加水幕和不施加水幕玻璃的破裂脱落行为进行了比较分析。研究发现,当钢化玻璃温度较低时(火灾初期)开启水幕会起到很好的降温冷却效果,但是当玻璃温度较高以后(火灾中后期)再开启水幕会加速钢化玻璃的破裂脱落。在本文实验工况下,水幕能对6mm钢化玻璃起保护作用的临界温度为250℃,即超过该临界温度水幕将导致玻璃破裂,而在对照实验中无水幕作用时6mm钢化玻璃可承受400～500℃高温仍不破裂。造成这一现象的原因是受热玻璃与冷的水幕接触时瞬间产生巨大的热应力导致玻璃破裂。水幕不仅会加速高温玻璃的破裂过程,还会增加其脱落比例,因为水幕与玻璃接触时会产生冲击作用。对非钢化玻璃的研究发现,Low-E玻璃出现与钢化玻璃类似的现象。本实验工况下无水幕作用时6mm Low-E玻璃的平均破裂温度为93.6℃。而当Low-E玻璃温度超过70℃以后施加水幕则会加速其破裂脱落。对于浮法玻璃则没有该现象,在浮法玻璃正常破裂温度前施加水幕没有导致其提前破裂。造成Low-E玻璃比同厚度的浮法玻璃更容易破裂的原因是由于Low-E玻璃一侧表面镀了一层低辐射膜,使得Low-E玻璃的传热系数U大大降低,这导致面对相同强度火源辐射时透过Low-E玻璃的热量更少,因此Low-E玻璃更容易达到导致其破裂的临界温差,而火灾中温差引起的热应力是玻璃破裂的主要原因。本文进一步对水幕吸热量、水幕厚度、水幕流速、水幕利用率等参数进行了定量计算,更加准确的揭示了水幕对玻璃的保护作用。
[Abstract]:For reasons such as beautiful, economical and transparent, glass is more and more widely used in modern architecture, and the variety of glass is becoming more and more diverse. But when the fire occurs, glass curtain wall or glass window structure is the weakest link in the building. It is easy to break off and fall into a new vent. Once a new vent is formed, it is bound to come into being. To increase the spread of the fire, influence people to evacuate, causing greater loss of life and property. In order to extend the time of fire prevention in the fire, the building usually equipped with corresponding spray or water curtain facilities to reduce the temperature of glass when the fire occurs.
Scholars at home and abroad have studied the water protection effect of ordinary glass, toughened glass, fireproof glass and so on. Some qualitative conclusions have been obtained. On the basis of a large number of domestic and foreign literature, the effect of water curtain on the fracture behavior of glass has been studied and analyzed in a large amount.
According to the purpose and plan of the experiment, this paper designed and machined an experimental device composed of water supply system, water curtain spray system, fire source simulation system, measurement control system and water curtain recovery system.
In this paper, three kinds of glass, which are most widely used in tempered glass and non tempered Low-E and float glass, are studied in the experiment. In the experiment, the glass specimens were heated to different temperatures and the experimenters opened the water curtain manually. The behavior of glass breaking and breaking off when the curtain was opened at different stages of fire was simulated. The rupture and drop behavior of water curtain glass was compared and analyzed.
It is found that when the tempered glass is low (in the early fire) the opening of the water curtain will be a good cooling and cooling effect, but when the glass temperature is higher (in the later period of the fire), the opening of the water curtain will accelerate the rupture and fall off of the tempered glass. In this paper, the critical temperature of the water curtain to protect the 6mm tempered glass is 250 degrees centigrade. That is, over the critical temperature water curtain will cause glass rupture, and in the control experiment, the 6mm tempered glass can withstand a high temperature of 400~500 degrees centigrade without the action of a water curtain. The cause of this phenomenon is that the heated glass is in contact with the cold water curtain and produces a huge thermal stress at the moment that the glass breaks. The water curtain not only accelerates the high temperature glass. The breakage process will also increase its shedding ratio, because the water curtain will impact when it contacts with glass.
The study of non tempered glass shows that Low-E glass appears similar to that of tempered glass. The average rupture temperature of 6mm Low-E glass is 93.6 C when no water curtain action is used in this experiment, and when the temperature of Low-E glass exceeds 70 degrees, it will accelerate its rupture and fall off. For float glass, there is no such phenomenon in float glass. The application of the water curtain before the normal rupture temperature did not cause its premature rupture. The cause of the more prone to rupture of Low-E glass than that of the same thickness of float glass was due to a low radiation coating on the side surface of the Low-E glass, which greatly reduced the heat transfer coefficient U of the Low-E glass, which led to the heat of the Low-E glass through the radiation of the same intensity fire source. Therefore, Low-E glass is more likely to reach the critical temperature difference leading to its breakage, and the thermal stress caused by temperature difference in fire is the main reason for the rupture of glass.
In this paper, the parameters such as water curtain heat absorption, water curtain thickness, water curtain flow velocity and water curtain utilization ratio are quantitatively calculated, and the protective effect of water curtain on glass is revealed more accurately.

【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ171.1

【参考文献】