CRACK PREDICTION OF HIGH DURABLE CONCRETE STRUCTURES BASED ON FRACTURE MECHANICS

研究了声发射技术在断裂力学中的应用，并配备了相应的实验装置。通过对素混凝土和纤维混凝土的断裂力学参数的试验研究，阐明了在混凝土裂缝扩展分析中应考虑断裂力学参数的尺寸效应。将声发射波形定量分析方法发展为SiGMA程序，并应用于板试件的单轴压缩试验。结果证实了SiGMA程序识别裂纹位置，裂纹类型和裂纹方向的有用性。用边界元法分析了混凝土中任意方向裂纹的扩展。分析过程是如此有效，在实验中获得的裂纹轨迹很容易预测的边界元分析。为了确认裂纹运动学的SiGMA程序，后分析开发。基于断裂力学理论，研究了碳纤维和钢纤维等高耐久性混凝土的裂缝成核问题。在缩尺模型研究中证实了边界元法预测裂纹的能力。

An application of acoustic emission (AE) techniques to fracture mechanics is investigated and experimental devices for the research purpose are equipped. Fracture mechanics (FM) parameters are studied in experiments of plain and fiber-reinforced concrete, and it is clarified that the size effect of FM parameters should be taken into account for the analysis of crack propagation in concrete. Quantitative AE waveform analysis is developed as SiGMA procedure and is applied to uniaxial compression tests of plate specimens. Results confirm the usefulness of the SiGMA procedure to identify crack locations, crack types, and crack orientations. The boundary element method (BEM) is applied to analyze crack propagation in concrete in arbitrary directions. The analytical procedure is so effective that crack traces obtained in experiments are readily predicted by the BEM analysis.In order to confirm crack kinematics determined by the SiGMA procedure, a post-analysis is developed. Crack nucleation in high durable concrete such as carbon-fiber and steel-fiber reinforced concrete is studied on the basis of fracture mechanics. The ability of the crack prediction by BEM is confirmed in the scaled-down model study.