【摘要】 本研究基于相场法构建纤维-界面-基体三相细观模型，研究了钢纤维增强超高性能混凝土(Steel Fiber reinforced Ultra-High Performance Concrete, SF-UHPC)横向拉伸载荷下的裂纹扩展与损伤失效机制．引入有限宽度界面层，模拟了裂纹在界面区域的萌生、偏折及扩展行为，并对比分析了SF-UHPC、钢纤维增强普通混凝土(Steel Fiber reinforced Normal Concrete, SF-NC)及玄武岩纤维增强超高性能混凝土(Basalt Fiber reinforced UltraHigh Performance Concrete, BF-UHPC)在含有初始基体缺陷、含有初始界面缺陷以及无初始缺陷三种情况下的失效模式．结果表明：本文采用的方法可以实现纤维增强水泥基材料基体-界面复杂损伤演化机制的数值模拟．SF-UHPC表现出以界面主导裂纹扩展为主的失效机制，而SF-NC更多的是基体脆性断裂，BF-UHPC则是纤维断裂-界面削弱-基体断裂多阶段的特征．SF-UHPC在三种工况中均表现出最佳抗裂性能和延性，无初始缺陷时，SF-UHPC裂纹仍是从界面处萌生，与界面裂纹模拟结果接近，峰值承载力和断裂位移均最高，峰值荷载分别较SF-NC和BF-UHPC提升210.3%和46.3%，延性提升113.0%和8.89%.更多还原

【Abstract】 This study established a mesoscopic model of fiber-matrix interface with three phases based on the phase field method to investigate the crack propagation and damage failure mechanism of steel fiber reinforced ultra-high performance concrete(SFUHPC) under transverse tensile load. A finite-width interface layer was introduced to simulate the initiation, deflection and propagation of cracks in the interface region. The failure modes of SF-UHPC, steel fiber reinforced normal concrete(SF-NC) and basalt fiber reinforced ultra-high performance concrete(BF-UHPC) under three conditions, namely, with initial matrix defects, with initial interface defects and without initial defects, were compared and analyzed. The results show that the method adopted in this paper can realize the numerical simulation of the complex damage evolution mechanism of the matrix-interface of fiberreinforced cement-based materials. SF-UHPC shows a failure mechanism dominated by interface-controlled crack propagation, while SF-NC is more characterized by brittle matrix fracture, and BF-UHPC exhibits a multi-stage feature of fiber fractureinterface weakening-matrix fracture. SF-UHPC shows the best crack resistance and ductility in all three conditions. Even without initial defects, cracks in SF-UHPC still initiate from the interface, which is close to the simulation results of interface cracks. The peak bearing capacity and fracture displacement are the highest, with the peak load increased by 210.3% and 46.3%, respectively, compared with SF-NC and BF-UHPC, and the ductility increased by 113.0% and 8.89%, respectively.更多还原