PC箱梁墩顶块水化热温度冲击模型及空间仿真

Space simulation and hydration heat attack model for pier-on mass of PC box girder

针对目前PC箱梁墩顶块在施工过程中由于水化热导致出现裂缝现象,结合实际工程,综合考虑混凝土密度,比热容,热传导系数的温度时变效应,建立水化热温度冲击模型,采用单元生死技术和子模型技术对PC箱梁墩顶块水化热温度场进行空间数值仿真。经与实测数据对比说明:水化热温度冲击模型准确、实用;腹板与底板、腹板与顶板、腹板与横隔板交合处混凝土浇筑量较大,产生大量水化热,导致浇注温度很高;并向表面依次降低,由里及外温度梯度分布宽度逐渐小;采用单元生死技术能有效模拟混凝土箱梁分层浇筑或多层浇筑;子模型技术适合PC箱梁墩顶块局部精细分析,可解决单元划分所导致的复杂结构水化热热量传导梯度过大及阶跃现象。该成果对工程实际具有一定的参考价值。

In order to investigate the earlier temperature crack phenomenon of pier-on mass for concrete box girder during construction caused by hydration heat temperature, a hydration heat attack model is proposed which integrates the time-dependent effect of concrete density, specific heat and heat conductivity. The hydration heat temperature field of pier-on mass for PC box girder is modeled using element birth and dead technique and sub-model technique. The results indicate that hydration heat attack model is accuracy and practical; hydration heat at the copulation location of web plate and upper plate and floor plate as well as cross plate is huge, and thus the hydration heat temperature is very high while gradually decreases from the inner layer to the outer layer. It is effective for applying the birth and death technology of element to simulate the layer-cast for pier-on mass of concrete box girder and using sub-model technique adapt to model the complex structure of pier-on mass for PC box girder and effectively solve hydration heat conductivity step phenomenon.