高应变率下多尺寸聚丙烯纤维混凝土动态压缩力学性能研究

采用Φ74 mm的分离式霍普金森压杆(Split Hopkinson pressure bar,SHPB)试验装置,对两种尺寸聚丙烯细纤维和一种尺寸聚丙烯粗纤维单掺及混掺的混凝土试件进行冲击压缩试验,对比分析粗、细纤维及不同纤维掺量比的多尺寸纤维混凝土试件在五种不同应变率下的动态压缩强度、动态压缩变形、动态压缩韧性和破坏特征,研究聚丙烯纤维混凝土的动态压缩力学性能.结果表明:随应变率的增加,素混凝土及纤维混凝土的动态压缩强度、动态压缩变形和动态压缩韧性表现出显著的应变率效应;在试验应变率范围内,粗聚丙烯纤维混凝土的动态抗压强度最高,相对素混凝土增幅为132.36％～213.85％;多尺寸聚丙烯纤维混凝土的动态强度增长因子与素混凝土基本一致;掺入多尺寸聚丙烯纤维可有效增大混凝土在不同应变率下的动态峰值应变和动态极限应变;多尺寸聚丙烯纤维混凝土的动态极限韧性较高,其中细聚丙烯纤维含量为1.2 kg/m3时混凝土动态极限韧性最高,增幅为121.11％.

A Study on Dynamic Compressive Mechanical Properties of Multi-size Polypropylene Fiber Concrete Under High Strain Rate

Impacting compression tests of fine polypropylene fibers in two sizes and thick polypropylene fibers in one size,single-doped and mix-doped with concrete were conducted by 74 mm diameter split Hopkinson pressure bar (SHPB).Multi-size polypropylene fiber concrete specimens with coarse,fine fiber and different fiber content at 5 different strain rates under dynamic compressive strength,dynamic compressive deformation,dynamic compressive toughness and failure forms were compared and analyzed.The dynamic mechanical properties of polypropylene fiber were studied.The results showed that the dynamic compressive strength,dynamic compression deformation and dynamic compression toughness of concrete and fiber concrete show a significant strain rate effect with the increase of strain rate.In the range of strain rate,the dynamic compressive strength of coarse polypropylene fiber reinforced concrete is the highest,and in comparing with that of the plain concrete increased by 132.36％-213.85％.The dynamic compressive strength growth factor of multi-scale polypropylene fiber concrete is basically the same with that of plain concrete.The dynamic peak strain and ultimate strainof concrete under different strain rates can be increased effectively by adding polypropylene fiber.The dynamic ultimate toughness of multi-scale polypropylene fiber concrete is higher than that of polypropylene fiber concrete,and the dynamic ultimate toughness is the highest when the content of fine polypropylene fiber is 1.2 kg/m3,and the growth rate is up to 121.11％.