轻骨料纤维喷射混凝土动态力学特性试验

为提高轻骨料喷射混凝土喷层支护承受动态抗压强度能力,以普通C20喷射混凝土配比为基准,将3种不同掺量的陶粒与聚丙烯纤维进行组合,配制出了9组轻骨料纤维喷射混凝土(lightweight aggregate fiber shotcrete,LAFS),进行了一维分离式霍普金森压杆(SHPB)冲击及扫描电镜(SEM)试验,同时借助MATLAB数值计算软件,拟合出陶粒-聚丙烯纤维掺量与LAFS动态抗压强度预测模型.研究表明:陶粒掺量与聚丙烯纤维掺量对LAFS动态抗压强度的影响是交互的,同陶粒掺量下,不同的聚丙烯纤维掺量,对LAFS动态压缩性能有很大差异,反之亦然;混凝土基体中均匀分布的陶粒与乱向分布的聚丙烯纤维网,与混凝土基体共同受力,使得LAFS应力-应变曲线屈服平台明显、韧性增强;本试验条件下陶粒与聚丙烯纤维掺量较好的组合为:49.81 kg/m3 +0.91 kg/m3、99.67 kg/m3+ 1.82 kg/m3.拟合得到的LAFS动态抗压强度模型与研究成果可为LAFS推广及配合比确定起到参考.

Dynamic Mechanical Properties Test of Light-aggregate Fiber Shotcrete

To improve the ability of light aggregate shotcrete sprayed layer support to withstand dynamic compressive strength. The common shotcrete ratio was used as a benchmark. The combination of three different blending amounts of ceramic granules and polypropylene fibers was carried out. Nine groups of Lightweight Aggregate Fiber Shotcrete (LAFS) were formulated. One-dimensional SHPB impact and SEM scanning electron microscopy tests were carried out. Also with the help of Matlab numerical calculation software. A model for predicting the dynamic compressive strength of LAFS with the amount of ceramic pellets-polypropylene fiber doping was fitted. It was shown that the effects of ceramic pellets and polypropylene fiber doping on the dynamic compressive strength of LAFS were interactive. The dynamic compressive properties of LAFS differed significantly for different amounts of polypropylene fibers at the same ceramic particle admixture and vice versa. The uniformly distributed ceramic particles in the concrete matrix with the disordered distribution of polypropylene fiber network. The LAFS stress-strain curve yield plateau is obvious and the toughness is enhanced by the joint stress with the concrete matrix; the better combinations of ceramic particles and polypropylene fiber admixture under this test condition are: 49.81 kg/m3+0.91 kg/m3, 99.67 kg/m3+1.82 kg/m3. The fitted LAFS dynamic compressive strength model and the research results of this paper can be used for LAFS promotion and matching ratio determination.