中文摘要：

针对超高性能水泥基复合材料和基体砂浆，采用三点弯曲梁进行不同种类纤维、不同尺寸以及不同初始缝高比的静载断裂试验。并且在静载断裂试验的基础上进行初步动态断裂试验。依据双K断裂准则计算断裂参数，分析初始缝高比和不同种类纤维对断裂韧度的影响。研究动态断裂作用下超高性能水泥基复合材料承载能力和刚度的退化规律。试验结果表明：随着初始缝高比的增大，超高性能水泥基复合材料和基体砂浆的起裂断裂韧度表现为不变的趋势，失稳断裂韧度增加。进口纤维在改善极限荷载和增韧效果方面作用明显，国产纤维极限荷载的改善效果优于增韧效果。经过动态断裂作用的超高性能水泥基复合材料承载能力和刚度均有所下降；不带裂缝试件在整个疲劳过程中刚度退化不明显，带裂缝试件在疲劳过程中刚度退化过程可描述为：快-慢-快三个过程。

英文摘要：

Using the three-point bending beams with different kinds of fiber, different specimens sizes and different initial seam height ratio has carried on the static load fracture experiments,which directed at engineered cementitious composites and matrix.And on the basis of the static load fracture tests conducted preliminary dynamic fracture test.Based on the double-K fracture criterion to calculate the fracture parameters and analyz the initial seam height ratio and the influence of different kinds of fiber on fracture toughness.Moreover, study bear- ing capacity and stiffness degradation law of engineered cementitious composites under dynamic fracture load.Experimental results showed that with the increase of initial seam height ratio ,engineered cementitious composites and matrix the initial fracture toughness KICini showed the same trend, and unstable fracture toughness KICini increase of instability.Imported fiber in improvement of ultimate load and toughening effect obviously, the improvement of the domestic fiber limit load effect was better than that of toughening effect.Through dynamic fault- ing load engineered cementitious composites bearing capacity and stiffness were declined.Without fracture specimen rigidity degeneration was not obvious in the whole process of fatigue, and fracture specimens in the process of fatigue stiffness degradation process can be described as fast-slow-fast three process.