长悬臂混凝土盖梁水化热监测与分析
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摘要
为避免长悬臂混凝土盖梁施工期间产生较高的水化热导致温度裂缝,对两座长悬臂盖梁开展了水化热实时监测,并在盖梁内部埋置相应的应力传感器同步实测盖梁混凝土早龄期力学性能。采用有限元软件Midas FEA建立相应梁段的时变模型,研究盖梁混凝土水化热温度场和应力场,并对绝热温升进行参数分析。结果表明:长悬臂盖梁在施工期间会产生持续10 d的水化热,在混凝土浇筑后快速达到峰值温度,此时盖梁外部混凝土处于拉应力状态,若内外温差过大容易出现温度裂缝。所以实时监测控制和长悬臂盖梁水化热非常必要。
In order to avoid the temperature cracks caused by hydration heat during the construction of long-cantilever capping beam, the real-time monitoring of hydration heat is carried out for two long-cantilever capping beams, and also the relevant stress sensors are installed in the capping beams to synchronously measure the mechanical property of concrete early age of capping beams. The finite element software Midas FEA is used to establish the time-varying model of the beam sections, to study the temperature field and stress field of the hydration heat of concrete capping beam, and analyzes the parameters of adiabatic temperature rise. The results show that the long-cantilever capping beams will produce the hydration heat for 10 days during the construction of long-cantilever capping beam, and the peak temperature will rapidly reach after concrete pouring. At the moment, the external concrete of capping beam is at the tensile stress state. It is easy to cause the temperature cracks if the internal and external temperature difference is too big. So it is very necessary to monitor and control the hydration heat of long-cantilever capping beam in the real time.
In order to avoid the temperature cracks caused by hydration heat during the construction of long-cantilever capping beam, the real-time monitoring of hydration heat is carried out for two long-cantilever capping beams, and also the relevant stress sensors are installed in the capping beams to synchronously measure the mechanical property of concrete early age of capping beams. The finite element software Midas FEA is used to establish the time-varying model of the beam sections, to study the temperature field and stress field of the hydration heat of concrete capping beam, and analyzes the parameters of adiabatic temperature rise. The results show that the long-cantilever capping beams will produce the hydration heat for 10 days during the construction of long-cantilever capping beam, and the peak temperature will rapidly reach after concrete pouring. At the moment, the external concrete of capping beam is at the tensile stress state. It is easy to cause the temperature cracks if the internal and external temperature difference is too big. So it is very necessary to monitor and control the hydration heat of long-cantilever capping beam in the real time.
引文
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[2]康良桢.大体积盖梁的施工与控制[J].公路工程,2002,27(2):70-71.
[3]王国华.大悬臂盖梁钢支撑施工技术的应用[J].中国市政工程,2013(4):20-21.
[4]苟季.大体积混凝土水化热对结构的影响研究[D].南宁:广西大学,2008.
[5]彭兵田.承台大体积混凝土水化热试验分析[J].水运工程,2005(7):14-16.
[6]汪建群,方志.大跨预应力混凝土箱梁桥施工期腹板开裂研究[J].湖南大学学报(自然科学版),2012,39(5):1-7.
[7]蔡绍怀,左怀西.高强混凝土的抗裂强度[J].土木工程学报,1992,25(2):23-31.
[8]汪建群,方志,刘杰.大跨预应力混凝土箱梁水化热测试与分析[J].桥梁建设,2016,46(5):29-34.
[9]朱伯芳.水工混凝土的温度应力与温度控制[M].北京:清华大学出版社,1992:91-97.
[10]陈志坚,顾斌.大型混凝土箱梁水化热温度场的数值模拟[J].公路交通科技,2012,29(3):64-69.
[11]朱伯芳.考虑温度影响的混凝土绝热温升表达式[J].水力发电学报,2003(2):69-73.
[12]张子明,宋智通,黄海燕.混凝土绝热温升和热传导方程的新理论[J].河海大学学报(自然科学版),2002,30(3):1-6.