摘要
受水化放热的影响,大体积混凝土在早龄期阶段涉及多个物理场作用,极易发生损伤、开裂等不利行为,会对结构服役期内的耐久性和安全性产生严重的影响。针对此问题,该文基于经典损伤理论框架,发展了一类适用于早龄期大体积混凝土的化学-热-力多场耦合模型,综合地反映了早龄期混凝土的开裂、徐变、温度变形、自收缩变形和龄期效应。通过将水化反应方程与热传导方程联立建立了化学-热场耦合作用模型。进而,基于弹塑性损伤理论框架搭建本构关系,引入考虑损伤影响的微观应力-固化理论以刻画混凝土的线性徐变和非线性徐变,根据温度和水化度的变化求解热膨胀变形和自收缩变形,并考虑了随龄期变化的混凝土力学性能的影响。结合相应的显式求解算法,将上述多场耦合模型应用于Maridal涵洞早龄期力学行为的模拟分析,并探究了混凝土徐变变形的影响。计算结果表明:该文模型可以实现对早龄期大体积混凝土开裂过程的准确模拟,对早龄期混凝土受力性能和开裂行为的研究具有一定的参考意义。
Influenced by hydration of concrete,the early-age behavior of a massive concrete structure is a multiphysical field coupling process and it is prone to damage,to crack and to cause other harmful behaviors,which imposes a detrimental impact on the structural durability and safety in a long-term service period.To solve this problem,within the framework of classical damage mechanics,this paper develops a multi-field coupling model which comprehensively reflects the early-age behaviors of massive concrete,including cracking,creep,thermal deformation,autogenous shrinkage deformation and aging effect.A chemo-thermal model is established by combining the equation of hydration reaction and the heat transfer equation.The stress-strain relationship is based on the framework of elastoplastic damage theory.The damage-dependent microprestress-solidification theory is introduced to account for both linear creep and nonlinear creep.The thermal deformation and autogenous shrinkage deformation are described by the change of the temperature and the degree of hydration,respectively.The aging effects of concrete mechanical properties are also considered.Through the proposed model and the corresponding explicit numerical algorithm,the numerical simulation of the Maridal culvert is carried out,where the influence of concrete creep is investigated.Numerical results suggest that the model can predict the early-age cracking behavior of massive concrete structures and provides a meaningful reference for the analysis of mechanical behaviors of early-age concrete.
作者
王晴
任晓丹
WANG Qing;REN Xiao-dan(College of Civil Engineering&State Key Laboratory of Disaster Reduction in Civil Engineering,Tongji University,Shanghai 200092,China)
出处
《工程力学》
EI
CSCD
北大核心
2023年第3期225-237,共13页
Engineering Mechanics
基金
国家自然科学基金项目(52078361)
上海市教育委员会科研创新计划项目(2017-01-07-00-07-E00006)。
