基于DIC技术的自密实混凝土界面裂缝扩展规律研究

采用自密实混凝土作为堆石混凝土坝的抗冲磨层并与坝体进行一体化浇筑成型是一种新构造，其中抗冲磨层与坝体的界面性能至关重要。通过制作600 mm×600 mm×600 mm自密实混凝土（SCC）试件（C40SCC、C25SCC）及C40、C25SCC分层浇注试件（C40-C25SCC），结合数字图像技术（DIC）开展劈裂抗拉试验，分析了自密实混凝土界面裂缝扩展规律。结果表明：SCC断面破坏形态表现为骨料劈裂和剥落2种破坏形式；C40SCC、C25SCC及C40-C25SCC劈裂抗拉强度分别为1.861、1.416和1.362 MPa；基于DIC技术获取了裂缝相关参数，其中C40-C25SCC裂缝最大开口宽度、扩展时间均为最大，分别为0.125 mm、10.667 ms，C25SCC裂缝最大扩展速度最快，为10.12 m/s。研究表明：骨料的存在及粒径大小改变了试件破坏形态，影响了裂缝开口宽度及扩展速度变化。

Crack propagation behavior of self-compacting concrete interface based on DIC method

A novel engineering structure is introduced, in which the self-compacting concrete is used as the anti-abrasion layer of the rock-filled concrete dam, and then cast in place with the dam body. Therefore, the performance of the interface between the anti-abrasion layer and the dam body is crucial to the stability of the whole structure. 600 mm×600 mm×600 mm self-compacting concrete (SCC) specimens (C40SCC, C25SCC) and layered pouring specimens (C40-C25SCC) were prepared for the splitting tensile tests, and the digital image correlation (DIC) technique was adopted for the analysis of the crack propagation behavior at the SCC interface. The results show that the failure modes of SCC were the splitting and spalling of aggregates; the splitting tensile strengths of C40SCC, C25SCC and C40-C25SCC were 1.861, 1.416 and 1.362 MPa, respectively. The crack-related parameters were obtained based on DIC technique, among which the maximum crack opening width and propagation time of C40-C25SCC were the largest, measuring 0.125 mm and 10.667 ms, respectively. The fastest crack propagation speed was observed in C25SCC, which was 10.12 m/s. The study demonstrates that the presence and size of aggregates affect the failure mode of the specimens, as well as the variation of crack opening width and propagation speed.