钢纤维混凝土动态压缩与拉伸力学特性试验研究

Experimental Study on Dynamic Compressive and Tensile Mechanical Properties of Steel Fiber Reinforced Concrete

为探究钢纤维含量对混凝土动态压缩和拉伸力学特性的影响机制,采用霍普金森压杆(SHPB)装置开展了不同冲击气压、不同钢纤维体积含量(0%C50素混凝土、2%、3%和4%)的混凝土试样动态压缩和动态巴西劈裂试验,并结合高速摄影揭示了试样裂纹的动态演化过程。试验结果表明:在同一冲击气压下,钢纤维混凝土试样的动态压缩强度和动态劈裂拉伸强度与钢纤维含量呈正相关,其吸能程度和破碎程度也呈正相关。钢纤维可有效抑制混凝土的破碎,阻碍钢纤维混凝土试样对冲击能量的吸收与耗散。其中,钢纤维混凝土试样吸能率的上限区间为30%~36%。钢纤维对混凝土的动态劈裂拉伸强度的提升显著高于其对动态抗压强度的提升,且对于较高混凝土强度、甚至有抗爆需求的钢纤维混凝土,结合试验数据、工程经济成本、技术可控性等方面考虑,2%~3%钢纤维含量可作为混凝土增韧的合理区间。钢纤维对混凝土试样动态劈裂和压缩破坏的作用机理不同,动态劈裂过程中,钢纤维可显著阻碍和约束混凝土裂缝的动态扩展;而动态压缩过程中,钢纤维和混凝土之间因发生剥离而导致增韧作用失效。

In order to investigate the influence mechanism of steel fiber content on the dynamic compression and tensile mechanical properties of concrete,this study conducted dynamic compression and dynamic Brazilian splitting tests on concrete samples with varying impact pressure and steel fiber volume contents(0%C50 element concrete,2%,3%,and 4%)using a Hopkinson pressure bar(SHPB)device.Additionally,high-speed photography was employed to reveal the dynamic evolution process of cracks.The test results demonstrate that under the same impact pressure,both the dynamic compressive strength and dynamic splitting tensile strength of steel fiber reinforced concrete samples exhibit a positive correlation with the content of steel fiber.Furthermore,there is also a positive correlation between energy absorption capacity and degree of crushing,indicating that steel fibers effectively inhibit concrete crushing while preventing excessive energy absorption and dissipation in these samples.The upper limit for energy absorption rate in steel fiber reinforced concrete samples ranges from 30%to 36%.Notably,compared to its effect on dynamic compressive strength,steel fibers significantly enhance the dynamic splitting tensile strength of concrete.For applications requiring high-strength or anti-violence characteristics in combination with cost-effectiveness,technical controllability,and test data analysis;incorporating a reasonable range for toughening can be achieved by including 2%~3%steel fiber content into high-strength concrete.Moreover,it is important to note that the action mechanism of steel fibers differs when considering their effects on both dynamic splitting and compression failure in concrete samples.Steel fibers significantly impede crack propagation during dynamic splitting processes;however,separation between the fibers themselves leads to ineffective toughening during dynamic compression."