CRACK PREDICTION OF HIGH DURABLE CONCRETE STRUCTURES BASED ON FRACTURE MECHANICS

研究了声发射（AE）技术在断裂力学中的应用，并配备了用于研究目的的实验装置。通过普通混凝土和纤维混凝土的试验研究了断裂力学（FM）参数，明确了混凝土裂纹扩展分析应考虑FM参数的尺寸效应。定量AE波形分析是作为SiGMA程序开发的，并应用于板样本的单轴压缩测试。结果证实了 SiGMA 程序在识别裂纹位置、裂纹类型和裂纹方向方面的有用性。边界元法（BEM）用于分析混凝土中任意方向的裂纹扩展。该分析程序非常有效，实验中获得的裂纹痕迹很容易通过 BEM 分析进行预测。为了确认 SiGMA 程序确定的裂纹运动学，开发了后期分析。基于断裂力学研究碳纤维、钢纤维混凝土等高耐久性混凝土的裂纹形核。边界元法的裂纹预测能力在缩小模型研究中得到了证实。

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.