关于混凝土声学特性试验研究

An Experimental Study on the Acoustic Characteristic of the Different Strength and Cracked Concrete Specimens

为分析混凝土的裂纹和强度对其声学特性的影响,运用控制变量法设计并进行了不同强度、不同裂纹混凝土试件声学特性试验。试验表明:当裂纹深度相同时,随着强度的增加,混凝土试件的声时明显降低,声速、振幅和频率在整体上有所提高,声波在裂纹处的能量损失率降低,其密实性和完整性有所提高;当强度相同时,随着裂纹深度的扩展,混凝土试件的声时延长,声速、振幅和频率明显降低,声波传递受阻程度加强,传播路径发生了改变,大量声波发生绕射、反射及散射等使得其能量衰减程度加大,密实性和完整性有所降低。试验成果为检测混凝土构件质量是否达标,损伤与否及其损伤程度大小提供可靠依据。

For the analysis of influences of concrete crack and strength on its acoustic characteristics, the method of controlling variable is designed and carried out to test the acoustic characteristic of various concrete specimens with different intensities and cracks. The experiments showed that, along with the increase of strength, the phonatory time of the concrete with the same depth of crack decreases significantly, the velocity of sound, the amplitude and the frequency are improved, the energy loss rate of wave is reduced at crack location and its density and integrity are slightly improved. While with the expansion of the crack depth when the strength is the same, the phonacory time of concrete specimen extends, its sound velocity, amplitude and frequency reduces significantly, suggesting that the intensity of blocking of acoustics transmission is strengthened and the propagation paths are changed, which result in lots of sound diffract, reflect and scatter around, so as to increase the degree of energy attenuation and reduce the integrity and density. The results of the experiments can be applied to the practical engineering, providing reliable basis for testing whether the quality of concrete reaches the standard, whether the concrete is damaged and the degree of damage .