As a kind of construction material with superior mechanical properties,ultra-high performance concrete (UHPC) can notably enhance the impact resistance of properties,which is of great significance to the life security under the military protective engineering.To reveal the principle of dynamic tensile fracture caused by explosive shock wave on the free surface of protective engineering,this paper,which is based on a series of spallation experiments using the split Hopkinson pressure bar,studies the impact of coarse aggregate type,content of steel fiber and strain rate on dynamic tensile property of UHPC.Results showed that coarse aggregate type has a marked influence on spall strength.Compared with that of granite and iron ore,the impact of basalt is the most remarkabale.Besides,with the increase of steel fiber content,the dynamic tensile property is improved notably.However,there exists a limitation on the contribution to the spall strength,approximately 4％.As to the impact of the strain rate,UHPC displays a remarkable strain rate effect,especially when the strain rate varies from 7 s-1 to 50 s-1.%超高性能混凝土(Ultra-high performance concrete,UHPC)作为一种具有超高物理力学性能的新型建筑材料,能显著提高军事防护工程的抗爆炸冲击能力,对保障防护工程中人员的生命安全具有重要意义.为揭示爆炸冲击波在防护工程自由面引起的动态拉伸破坏行为,利用霍普金森压杆装置(Split Hopkinson pressure bar,SHPB)对UHPC进行动态冲击拉伸试验,系统研究了粗集料种类、钢纤维掺量以及应变率对UHPC动态冲击拉伸性能的影响规律.结果表明:粗集料种类对UHPC的动态冲击拉伸强度有较显著的影响,相比于花岗岩和铁矿石,玄武岩粗集料对动态冲击拉伸性能的提高更为明显;UHPC的动态冲击拉伸强度会随着钢纤维掺量的增加而显著提高,但钢纤维掺量对UHPC动态拉伸强度的贡献存在4％的临界值;此外,UHPC表现出明显的应变率效应,当应变率为7～50 S-1时,其效应最为显著.
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