劣化作用后水工混凝土裂缝扩展及断裂性能研究

Through the fracture characteristics test of hydraulic concrete after degradation, the method to obtain the crack propagation length and the fracture process zone size and the method to calculate and analyze the fracture parameter are proposed. The softening constitutive curve will be determined. The effects of carbonation, wetting-drying cycle of sulfate solution and freezing-thawing cycle upon the crack propagation length, the fracture process zone size, the softening constitutive curve, the fracture parameter and the microstructure will be studied. On above basis, the concrete fracture mechanics theory, nonlinear finite element method, mathematic statistics analysis and geometric similarity method will be used to analyze the correlations of microstructure， deterioration and fracture characteristic. The crack propagation mechanism will be studied. The relationships between microstructure characteristic, deterioration indicator and fracture parameter, the quantitative relationships between deterioration indicator and microstructure characteristic and the probability distribution of the fracture parameter will be determined.The calculating model will be established for calculating crack propagation of hydraulic concrete, and the calculating mode will be established for calculating fracture parameter of hydraulic concrete.The expected results of the project will have important theoretical significance and practical value to rich and develop the fracture mechanics theory and to promote its application in the hydraulic engineering in severe environment.

通过劣化作用后水工混凝土断裂性能试验，提出获取裂缝扩展量和断裂过程区尺寸的试验方法以及断裂参数的计算与分析方法，确定软化本构曲线；研究碳化、硫酸盐溶液干湿循环和冻融循环作用对水工混凝土裂缝扩展量、断裂过程区尺寸、软化本构曲线、断裂参数以及微观结构的影响。在此基础上，利用混凝土断裂力学理论、非线性有限元、数理统计和几何相似等方法，分析微观结构与劣化作用以及断裂性能的相关性，研究裂缝扩展机理，确定水工混凝土微观结构特性与劣化指标间、断裂参数间的相关关系、劣化指标与断裂参数间的定量关系以及断裂参数的概率分布，建立反映劣化作用影响的裂缝扩展计算模型和断裂参数计算模式。项目预期成果对丰富和发展混凝土断裂力学理论，推动断裂力学在恶劣环境下水利工程中的应用具有重要的理论意义和实用价值。

裂缝作为水工混凝土最常见的病害之一，采用断裂力学理论研究混凝土裂缝扩展及断裂性能意义重大；本研究采用正交试验法设计了水工混凝土劣化作用试验，分析了碳化、硫酸盐溶液干湿循环和冻融循环作用作用对水工混凝土断裂韧度、裂缝扩展量和断裂过程区尺寸、软化曲线的影响；确定了劣化作用后水工混凝土断裂韧度概率分布，建立了反映劣化作用影响的裂缝扩展、断裂韧度计算模式。项目成果对丰富和发展混凝土断裂力学理论，推动断裂力学在恶劣环境下水利工程中的应用具有重要的理论意义和实用价值。