关键词: 混凝土断裂, 数字图像相关法, 初始缝高比, 全场应变及位移, 裂缝扩展

Abstract: For researching the effect of initial crack-depth ratio on fracture property of concrete, 15 three-point bending (TPB) beam specimens with three different initial crack-depth ratios of 0.2,0.3 and 0.4 were tested. Moreover, the full-field strain and displacement data of specimen surface was measured using the digital image correlation (DIC) method. A comparative analysis on the measured crack mouth opening displacement (CMOD), crack tip opening displacement (CTOD) and the critical effective crack extension length between the DIC method and the traditional clip gauge method was made. The results show that the values of CTOD and CMOD measured by two methods agree well with each other；The measured results of effective crack propagation length based on DIC method compared well with the results of the calculated formula and the error is less than 8%; The crack propagation path during the whole fracture process can be monitored with the horizontal direction strain diagram obtained by DIC method. Therefore, the DIC method can be applied in the concrete fracture experiment.

Key words: concrete fracture, digital image correlation method, initial crack-depth ratio, full field strain and displacement, crack propagation