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根据超声波在混凝土介质中传播的声速、首波幅值、波形,分析了大尺寸混凝土试样的内部缺陷和均匀性,并对其弹性模量、衰减系数、松弛时间等动态参数进行求解。为了与超声波检测结果对比,采用改进的Hopkinson压杆技术对同配比的圆柱形混凝土试样进行实验研究来测定其相应动态参数,并对比分析了两种方法的不同之处。实验结果表明:两种方法测定的动态弹性模量基本一致;HPB试验测得的衰减系数比超声波试验测得的值大,这说明HPB试验中存在动态损伤的影响;HPB试验测得的松弛时间比超声波测得的增加了近一倍,这表明了在高应变率下,混凝土试样的脆性得到了明显的增加。试验数据可以为工程应用提供借鉴。
According to the sound velocity, the first wave amplitude and the waveform of the ultrasonic wave propagating in the concrete medium, the internal defects and the uniformity of the large-size concrete specimen are analyzed, and the dynamic parameters such as the elastic modulus, the attenuation coefficient and the relaxation time are solved. In order to compare with the ultrasonic testing results, the Hopkinson pressure bar technology was used to experimentally study the cylindrical concrete specimens with the same ratio to determine the corresponding dynamic parameters, and the differences between the two methods were analyzed. The experimental results show that the dynamic modulus of elasticity measured by the two methods is basically the same; the attenuation coefficient measured by the HPB test is larger than the value measured by the ultrasonic test, indicating the dynamic damage in the HPB test; the relaxation time measured by the HPB test Nearly double the ultrasonic measurement, which shows that at high strain rate, the brittleness of concrete samples has been significantly increased. Experimental data can provide reference for engineering application.