混凝土冻融劣化后动态单轴抗压特性试验研究

Experimental studies of dynamic uniaxial compressive properties of concrete after freeze-thaw deterioration

为研究混凝土冻融循环后的动态力学性能,利用10 MN动静三轴仪对不同冻融劣化程度的混凝土在不同加载速率下进行单轴压缩试验,同时采集声发射数据分析试验过程中能量释放及损伤演化规律。最后,选用Weibull-Lognormal损伤本构模型,对试验数据进行拟合分析,并分析不同工况混凝土的损伤随应变的发展规律。研究结果表明:(1)相同冻融劣化程度时,随应变速率增加,峰值应力增大,峰值应变减小;冻融劣化程度会影响峰值应力的率敏感性;(2)在应变速率相同时,随冻融循环次数增加,峰值应力随之减小,峰值应变随之增大。(3)混凝土冻融劣化后应力应变关系峰前服从Weibull统计分布,峰后服从Lognormal统计分布。(4)在相同应变速率下,随着冻融循环次数的增加,混凝土的累计塑性应变整体呈增大趋势。

To study the dynamic mechanical properties of concrete after freeze-thaw deterioration, the uniaxial compression tests of concrete specimens with varied freeze-thaw deterioration degrees are carried out by 10 MN triaxial static-dynamic instrument under different loading rates. The laws of the energy release and the damage evolution are analyzed by using acoustic emission. The damage development patterns of concrete with the strain under different load combinations are studied based on the Weibull-Lognormal damage constitutive model and its fitting experimental results. The results show that：①For the concrete specimens with the same freeze-thaw deterioration degree, the peak stress increases with the increase of the strain rate, while the peak strain decreases. It indicates that the freeze-thaw deterioration degrees have influences on the sensitivity of the peak stress. ②For the concrete specimens with the same strain rate, the peak stress decreases with the increase of the number of freeze-thaw cycles, while the peak strain increases. ③The stress-strain relationship of the concrete specimens after freeze-thaw deterioration is subjected to follow Weibull statistical distribution before the peak stress, and follow Lognormal statistical distribution after the peak stress. ④For the concrete specimens with the same strain rate, the accumulative plastic strain of concrete generally increases with the increase of the number of freeze-thaw cycles.