摘   要：为探究含粗骨料超高性能混凝土单轴拉伸韧性及增强增韧机理，采用单轴拉伸法，研究含粗骨料超高性能混凝土的单轴拉伸性能；采用X射线计算机断层扫描技术和图像分析法，并引入纤维分散系数和纤维取向系数，对单轴拉伸试验后超高性能混凝土中钢纤维的真实分布进行表征；阐明了钢纤维分布与粗骨料、钢纤维分布与混凝土拉伸韧性之间的关系。试验结果表明，钢纤维以粗骨料为中心环绕分布；粗骨料对钢纤维分布具有不利影响，粗骨料掺量越大，粒径越大，纤维分散性越差，超高性能混凝土单轴拉伸韧性越低；钢纤维分布与超高性能混凝土单轴拉伸强度及韧性密切相关，随着纤维分散系数和取向系数的增大，超高性能混凝土单轴拉伸强度、韧性指数以及拉压比相应增大，韧性增强。

Abstract: In order to investigate the properties of uniaxial tension and mechanism of strengthening and toughening of ultra-high performance concrete containing coarse aggregate, the method of uniaxial tension is used to study the toughness of uniaxial tension; the method of X-ray computed tomography and image analysis introducing fiber dispersion coefficient and fiber orientation factor, is used to study the true distribution of steel fiber in ultra-high performance concrete. It illustrates the relationship between steel fiber distribution and coarse aggregate, steel fiber distribution and uniaxial tensile toughness. The experimental results reveal that steel fibers take coarse aggregate as the center, surround distributing, coarse aggregate having adverse effects on the steel fiber distribution, the more of coarse aggregate content, the larger of particle size, the poorer of fiber dispersion, the lower of uniaxial tension toughness. Steel fiber distribution is closely related to uniaxial tensile strength and toughness of ultra-high performance concrete. With increasing of fiber dispersion coefficient and the orientation factor, uniaxial tensile strength, toughness index and tension and compression ratio are increased, the toughness of concrete reinforced.