不同养护条件下玄武岩纤维混凝土动态压缩力学特性及能量耗散研究

Dynamic Compression Mechanical Characteristics and Energy Dissipation Law of Basalt Fiber Reinforced Concrete Under Different Curing Conditions

为探究冲击荷载作用下养护条件对玄武岩纤维混凝土力学性能的影响,采用分离式霍普金森压杆试验装置(SHPB)对不同养护龄期(1 d、3 d、7 d、14 d、28 d)及养护相对湿度(35%、55%、75%、95%)的玄武岩纤维混凝土开展动态单轴压缩试验,分析养护龄期及养护相对湿度对试件的平均应变率、峰值应力、能量耗散及分形维数的影响规律。结果表明:相同冲击荷载作用下试件平均应变率会随养护龄期的增长、相对湿度的增大而降低,峰值应力随之增大,养护龄期与平均应变率间呈指数负相关,与峰值应力间呈指数正相关;冲击荷载作用下试件能量时程曲线可分为三个阶段,其透射能、耗散能及破碎耗能密度均随养护龄期的增长、相对湿度的增大而增大,反射能随之降低,养护龄期的增长、相对湿度的增大会使试件水化产物增多,增强试件整体性;养护相对湿度为95%时,相较于养护龄期为1 d试件,养护龄期为3 d、7 d、14 d、28 d试件分形维数降幅分别为8.61%、13.91%、23.58%、26.68%,养护龄期减少、相对湿度降低会使试件破碎程度增加,分形维数随之增大。

In order to explore the effect of curing conditions on the mechanical properties of basalt fiber reinforced concrete under impact load,the dynamic uniaxial compression tests of basalt fiber reinforced concrete with different curing ages(1,3,7,14,28 d)and curing relative humidity(35%,55%,75%,95%)were carried out with split Hopkinson compression bar test device(SHPB).The effects of curing age and relative humidity on the average strain rate,peak stress,energy dissipation and fractal dimension of the specimens were analyzed.The results showed that under the same impact load,the average strain rate of specimens would decrease with the increase of curing age and relative humidity.The curing age had an exponential negative correlation with the average strain rate and an exponential positive correlation with the peak stress.The energy time history curve of the specimen under impact load could be divided into three stages.The transmission energy,dissipation energy and crushing energy density increased with the increase of curing age and relative humidity,and the reflection energy decreased with it.The increase of curing age and relative humidity would increase the hydration products of the specimen andenhance the integrity of the specimen.When the curing relative humidity was 95%,compared with the specimens with the curing age of 1 d,the decrease of the fractal dimension of the specimens with the curing age of 3 d,7 d,14 d and 28 d was 8.61%,13.91%,23.58%and 26.68%respectively.The reduction of curing age and relative humidity would increase the fracture degree of the specimen,and the fractal dimension would increase.