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为研究约束状态下早龄期混凝土的拉伸徐变性质,建立了基于水化度并考虑约束状态的早龄期混凝土拉伸徐变模型,推导出三维空间应力增量和应变增量关系式。对密闭状态下4组混凝土在不同养护温度下的自由收缩和约束应力发展进行了实测,应用实测结果推算模型参数,并验证了算法的正确性。最后用于某地下通道墙体约束应力发展的计算,并与由B3徐变模型得到的应力结果作了比较。研究结果表明:建立的基于水化程度并考虑约束状态的拉伸徐变模型较传统的B3徐变模型能够更好地体现混凝土早龄期的应力松弛效应,可用于约束状态下混凝土结构早龄期内应力发展预测,有助于对早期开裂风险进行正确评估。
In order to study the tensile creep properties of concrete in the early age under the restrained condition, a tensile creep model of early age concrete based on the degree of hydration and restraint was established, and the relationship between the stress increment and strain increment in three-dimensional space . The free shrinkage and restrained stress development of four groups of concrete under different curing temperatures were measured. The measured parameters were used to calculate the model parameters, and the correctness of the algorithm was verified. Finally, it is used to calculate the constraint stress development of an underground passage wall and compared with the stress results obtained from the B3 creep model. The results show that the established tensile creep model based on the degree of hydration and considering the constraint state can better reflect the stress relaxation effect of concrete in the early age than the traditional B3 creep model and can be used in the concrete structures aged The prediction of stress development during the period will help to correctly assess the risk of early cracking.