玄武岩纤维活性粉末混凝土在冲击载荷下的力学行为及本构关系

Mechanical Behavior and Constitutive Relationship of Basalt Fiber Reactive Powder Concrete Under Impact Loading

采用直径为50 mm的分离式霍普金森压杆(Split Hopkinson pressure bar,SHPB)对玄武岩纤维(Basalt fiber,BF)体积分数为0%、0.5%、1%和1.5%的活性粉末混凝土(Reactive powder concrete,RPC)进行高速冲击压缩试验,分析BF体积分数和应变率对RPC的动态抗压强度、极限应变、冲击韧性和破坏程度的影响,建立适用于玄武岩纤维活性粉末混凝土(Basalt fiber reactive powder concrete,BF-RPC)考虑损伤的动态本构方程。结果表明:RPC具有显著的应变率效应,即对于BF体积分数相同的RPC,加载应变率从60 s^(-1)增加到120 s^(-1)时,其动态抗压强度、动态强度增长因子、极限应变、冲击韧性以及破碎程度逐渐增加;BF的加入改变了RPC的冲击力学性能和破坏形态,当加载应变率不变,BF体积分数从0%增加到1.5%时,RPC动态抗压强度和冲击韧性随BF体积分数的增加呈现出先增大后减小的趋势,且BF的加入能够有效抑制裂纹的产生和扩展。综合来看,BF最优体积分数为0.5%;通过对试验应力-应变曲线进行拟合可知,基于考虑损伤的动态本构模型适用于掺加BF的RPC材料。

High-speed impact compression tests of reactive powder concrete(RPC)with 0%,0.5%,1%and 1.5%volume fraction of basalt fiber(BF)were carried out by using the 50 mm split Hopkinson pressure bar(SHPB).The effects of BF volume fraction and strain rate on the dynamic compressive strength,ultimate strain,impact toughness and failure degree of RPC were studied.A dynamic constitutive equation for basalt fiber reactive powder concrete(BF-RPC)considering damage was established.The results show that RPC has significant strain rate effect,and for RPC with the same volume fraction of BF,the dynamic compressive strength,dynamic strength growth factor,ultimate strain,impact toughness and crushing degree increase gradually when the loading strain rate increases from 60 s^(-1) to 120 s^(-1).The impact mechanical properties and failure morphology of RPC are changed by the addition of BF.When the volume fraction of BF with the same loading strain rate increases from 0%to 1.5%,the dynamic compressive strength and impact toughness of RPC first increase and then decrease with the increase of BF volume fraction,and the generation and propagation of cracks can be effectively restrained by the addition of BF.Overall,the optimal volume fraction of BF is 0.5%.By fitting the experimental stress-strain curves,it is known that the dynamic constitutive model considering damage is suitable for BF-RPC.