超高性能混凝土的冲击压缩性能及损伤演变规律

Impact Compressive Performance and Damage Evolution of Ultra-High Performance Concrete

掺2种不同形状的超细镀铜钢纤维,制备出性能优异的超高性能混凝土材料(UHPC),采用分离式Hopkinson压杆装置对UHPC材料进行了多次高速冲击压缩实验,研究了应变率、冲击次数、纤维种类及其混杂对该材料抗多次冲击性能的影响规律,采用X射线CT测试技术研究UHPC在多次冲击荷载作用下的动态损伤演变规律并对材料的损伤程度进行定量分析。结果表明:端勾型钢纤维对UHPC材料的增强、增韧效果略优于平直型钢纤维,掺加1%的平直型和2%端勾型钢纤维的材料具有最优异的静态和动态力学性能,提出了改进的动态增长因子模型解析式,与实验结果具有很好的吻合度。

Ultra-high performance concrete(UHPC) with excellent performance was prepared with two kinds of ultra-fine copper-plated steel fibers with different shapes. The multiple high-speed impact compression experiments of UHPC were carried out by a split Hopkinson pressure bar. The effects of strain rate, impact times, steel fiber types and hybrid fibers on the impact resistance of UHPC were investigated. The dynamic damage evolution of UHPC under multiple impact was characterized by X-ray computed tomography and the damage degree of UHPC was quantitatively analyzed. The results show that the reinforcing effect of end hook steel fibers on UHPC is a slightly better than that of straight steel fibers, and the material with 1% straight steel fibers and 2% end hook steel fibers has the optimum static and dynamic mechanical properties. An improved dynamic increase factor model was proposed. It is indicated that the simulated data by this model are in reasonable agreement with the experimental results.