为研究沥青混合料开裂及裂缝发展规律,通过SBS改性沥青混合料半圆试件三点弯曲实验,基于数字图像相关技术,利用VICG3D(video image corre-late,3D)采集系统对试件从加载到破坏全过程进行图像采集,并利用VICG3D 软件计算得到试件在受弯拉过程中三维位移场、应变场的变化及变化速率,分析并得出裂缝出现及发展规律;利用扫描电子显微镜对开裂试件断口进行观察,结合位移场、应变场及其变化速率揭示了试件开裂及裂缝发展的机理.结果表明,利用水平方向应变随时间变化规律可探究裂缝的发展轨迹;沥青混合料的开裂和裂缝发展沿沥青砂浆与粗集料的界面区发生,且趋向于表面情况相对差的集料的界面区;裂缝发展速率与界面区的厚度有关,可根据界面区厚度的代表值预测裂缝发展速率.
In order to study the cracking and the development of crack of asphalt mixture,three point bending of semicircular specimens of SBS asphalt mixture was conducted.Based on digital image correlate,VIC-3D (video image correlate,3D)acquisition system and the calculation software was used respectively during the whole damage process of specimens for image acquisition and calculation of displacement field,strain field and the changing rate of them,the cracking and the development of crack were obtained.Then the crack position of specimens was observed using scanning electron microscope and principle of cracking and the development of crack were explained with the help of the analysis of the displacement field and strain field.The results show that:using the horizontal strain variation law with time to explore the traj ectory of cracks is reasonable,the fracture of specimens and the development of fracture both occur along the interface of asphalt mortar and coarse aggregate area,and tend to the interface of aggregates which have poor interface.The development rate of fracture related to the thickness of the interface area,so it can be predicted according to a representative value of the thickness of interface layer.