高坝全级配混凝土断裂特性的相关性分析

Correlation Analysis of Fracture Characteristics of High Dam Fully-Graded Concrete

无粘结裂缝的产生可以被视为宏观裂缝发展的标志。为探究地震作用对全级配混凝土裂缝行为特征的影响,采用一种无粘结裂缝的识别模型,以数字图像相关技术作为试件裂缝扩展的监测手段,对不同加载速率(0.0001 mm/s、0.0010 mm/s、0.0100 mm/s)的全级配混凝土试件进行三点弯曲试验,考虑全级配混凝土裂缝扩展的率相关性。结果表明:对于不同加载时间间隔内的全级配混凝土试件,峰值前后均会产生无粘结裂缝,说明达到峰值荷载时预制裂缝处已发生开裂;试件的破坏主要集中在荷载加载至峰值荷载的50%以后;相同条件下,加载速率越慢,无粘结裂缝出现的阶段越早,随着加载速率增大,裂缝呈现细而长的特征。

The development of cohesionless cracks can be regarded as a sign of macroscopic crack development.An identification model of cohesionless cracks was adpoted with results of crack development by digital image correlation(DIC)method.Three-point bending tests were carried out on fully-graded concrete specimens with different loading rates(0.0001 mm/s,0.0010 mm/s,0.0100 mm/s),considering the rate correlation of crack propagation of fully-graded concrete.The results show that for the fully-graded concrete specimens with different loading time intervals,cohesionless cracks will occur throughout the peak load,indicating that the prefabricated cracks have cracked when the peak load is reached.The cracks of the specimen is mainly concentrated after the load is loaded to 50%of the peak load.Under the same conditions,the slower the loading rate is,the earlier the unbonded cracks appear.With the increase of the loading rate,the cracks are thin and long.