摘要
为了探讨高温下隧道衬砌混凝土材料性能的衰减规律和管片结构的高温损伤规律,进行了衬砌混凝土材料和构件的火灾烧损试验。结果表明,高性能混凝土的抗压强度、弹性模量和抗渗性能都随温度升高而迅速劣化,抗渗性能的降幅大于力学性能。掺入聚丙烯纤维对衬砌混凝土的高温爆裂有明显抑制效果,粗骨料的品种和颗粒形状对混凝土的高温损伤形式有明显影响。最后,在经典火灾评价模型的基础上,加入爆裂面积率、抗渗性能损失两个损伤指标特征,对试验中的衬砌管片火灾损伤进行评估。火灾作用2 h后,衬砌管片火灾损伤程度介于III^IV级(严重损伤与极度损伤)之间。
This paper would like to introduce the results of our exper- imental study into the mechanism of the concrete spalling and fire damage caused by the tunnel lining while exposed to the rising high temperatures of the fire by taking a Nanjing shield tunnel project un- der way as our study background. The paper has also discussed on the said background the attenuation of high performance concrete ma- terial properties and high-temperature injuries that may result from the lining segment structure. The results show that the compressive strength, the elastic modulus and the impermeability of the concrete might also be made degraded quickly with the temperature rising, when the impermeability fell more easily than its mechanical proper- ties. Furthermore, the technical tests also prove that the polypropy- lene （PP） fiber reinforced concrete tends to have superior perfor- mance in resisting explosive＂ spalling than the concrete without such additives. Moreover, the bonding strength of the transition interface is also a key factor influencing the likely spalling of the concrete. It is for this reason that it is suggested to increase the coarse aggregate with particles to increase sharp and angular anti-spaUing performancethan to use the rounded and smooth one, for the particle shape and variety of the coarse aggregate may have significant effects on fire damage deformed concrete. What is more, care should be taken of the self-decomposition reaction, which is likely to happen in calcare- ous aggregate at high temperature, for the part of aggregate would lat- er get crushed into powder as the result of burning in the fire. while the brittle failure and local burst occurs in siliceous aggregate, but the ingredients unchanged. Finally, spalling area ratio and imperme- ability damage is Suggested to add to the classic fire evaluation mod- el. A damage degree assessment of the tunnel lining segments is made, according to these index characteristic of fire injuries such as the temperature field of lining concrete, fire temperature characteris- tics, the appearance of damage, residual strength, and residual ca- pacity, and plus the above two index. After 2 h fire, the damage of lining segments ranged between Ⅲ-Ⅳ grade （serious injury and ex- treme damage）. The paper is available as a basis for raising the residual carrying capacity of the tunnel structure after fire and exten- sion of the limit of fire resistance of structure elements.
出处
《安全与环境学报》
CAS
CSCD
北大核心
2013年第5期159-164,共6页
Journal of Safety and Environment
基金
国家自然科学基金项目(41102171)
浙江省科技厅科技计划项目(2008C13041-2)
关键词
桥梁与隧道工程
火灾损伤
高温爆裂
聚丙烯纤维
粗骨料
抗渗性能
bridge and tunnel engineering
fire damage
explosionspalling under fire
PP fiber
coarse aggregate
imper-meability
