为研究加载速率和饱水作用对玄武岩纤维混凝土力学特性与破坏机理的综合影响,采用非金属超声波检测仪等装置对试件孔隙率、饱和含水率及纵波波速进行测量,利用万能试验机及直径为74 mm的分离式霍普金森压杆对干燥及饱水试件开展不同应变率下单轴压缩试验,分析应变率及饱水作用对试件纵波波速、应力-应变曲线、峰值应力及弹性模量的影响规律。结果表明:玄武岩纤维混凝土的孔隙度在1.89%~3.05%之间,试件孔隙度与饱和含水率间存在良好的线性正相关关系,饱水作用加快了试件内部纵波的传播速度;静载作用下饱水试件峰值应力低于干燥试件的8.6%,随着应变率的增加,饱水试件及干燥试件峰值应力及弹性模量均增大,试件存在明显的应变率效应,饱水试件应力增幅明显高于干燥试件,应变率达到130 s^-1时干燥饱水试件应力基本保持一致,当应变率达到160 s^-1时饱水试件峰值应力高于干燥试件的11.4%,弹性模量变化规律与强度变化保持一致;饱水作用对玄武岩纤维混凝土既存在侵蚀劣化作用,又存在水-纤维混凝土动力耦合强化作用,静载作用下水的软化作用及尖端水压力对裂隙的扩展作用降低试件抵抗外荷载能力,而动载作用下孔隙负压的存在及Stefan效应阻碍裂纹的扩展及试件的破坏,干燥及饱水试件应力相同时对应的临界应变率为130 s^-1。

To investigate the combined effects of loading rate and water saturation on the mechanical properties and failure mechanisms of basalt fiber reinforced concrete, non-metallic ultrasonic detectors and other devices were used to measure porosity, water saturation, and longitudinal wave velocity of the specimens. Compression tests were performed on saturated and dry specimens under different strain rates, using a universal testing machine and a split Hopkinson pressure bar with a diameter of 74 mm. The impacts of strain rate and water saturation on peak stress, elastic modulus, longitudinal wave velocity, and stress-strain relationships were also analyzed. Results showed that the porosity of basalt fiber reinforced concrete ranged from 1.89% to 3.05%, and a positive linear correlation was observed between the porosity of the specimens and their saturation levels. Water saturation accelerated the propagation of longitudinal waves inside the specimens. Under static loading conditions, the peak stress of saturated specimens was 8.6% lower than that of dry specimens, while the peak stress and elastic modulus of both types of specimens increased with increasing strain rates. Results also revealed a significant strain rate effect on specimens, with stress increase more pronounced in saturated specimens compared to dry ones. When the strain rate reached 130 s^-1, the stress levels in dry and saturated specimens were largely consistent. However, at a strain rate of 160 s^-1, the peak stress of saturated specimens was 11.4% higher than that of dry specimens. The elastic modulus showed a similar behavior to the strength. Water saturation led to erosion and degradation of the concrete as well as dynamic coupling strengthening effects between the water and fiber. Under static loading, softening effects of water and crack extension due to hydrostatic pressure at the crack tip reduced the ability of specimens to resist external loads. Under dynamic loading, negative pressure within pores and the Stefan effect hindered crack extension and the failure of the specimens. The critical strain rate corresponding to the same stress levels for both dry and saturated specimens was found to be 130 s^-1.