基于统计损伤理论的硫酸盐侵蚀混凝土本构模型研究

基于统计损伤理论及宏观试验现象,该文建立了考虑硫酸盐侵蚀影响的混凝土单轴、双轴压缩统计损伤本构模型。混凝土变形破坏被理解为细观断裂、屈服两种损伤模式的连续累积演化过程。硫酸盐侵蚀效应改变了混凝土微结构的组成成分和力学特征,进而改变了微裂纹萌生、扩展的形态以及损伤的累积演化过程,可通过改变断裂和屈服两种细观损伤机制演化过程的概率分布形态来模拟。分析结果表明:在硫酸盐侵蚀环境下,侵蚀程度的加深显著改变了混凝土细观损伤累积演化过程,最终导致混凝土宏观力学性能呈现先"强化"后"弱化"的现象。在此过程中,细观损伤演化过程呈现出明显地规律性,可由统计损伤模型中5个特征参数的变化规律表征。该文模型为复杂环境下侵蚀混凝土细观损伤过程预测和分析提供了新的方法和工具。

THE CONSTITUTIVE MODEL OF CONCRETE SUBJECTED TO SULFATE ATTACK BASED ON STATISTICAL DAMAGE THEORY

Based on the statistical damage theory and the test phenomenon,a statistical damage model for concrete under uniaxial and biaxial compression is proposed to consider the impact of sulphate attack.The deformation and failure of concrete is regarded as the continuous accumulation evolution of the two meso-damage modes,i.e.,rupture and yield.Sulfate erosion effect changes the component and mechanical characteristics in the microstructure of concrete,and then changes the initiation and propagation process of microcracks.The above effects could be simulated by changing the probability distribution which characterizes the evolution process of the two meso-damage modes.The results show that in the sulphate erosion environment,the meso-damage cumulative evolution process would be significantly changed with the deepening of the degree of erosion,and finally causes the macro-mechanical properties of concrete exhibiting the phenomenon of‘weakening’after‘strengthening’.During this process,the law of meso-damage evolution of the concrete shows obvious regularity,and it could be reflected by the five characteristic parameters in the statistical damage model.This paper presents a new method and tool to predict and analyze the damage mechanism of eroded concrete in complex environment.