钢筋混凝土梁结构中的声发射波衰减传播特征

Attenuation and Propagation Characteristics of Acoustic Emission Wave in Reinforced Concrete Beam Structure

为了解距离对弹性波传播的影响规律,制作了两种不同规格的钢筋混凝土梁,通过断铅模拟声发射信号,利用PAC-3声发射系统对弹性波在钢筋混凝土中传播的衰减规律进行试验研究。结果表明:频率、波速及振幅均随传播距离增加整体上呈衰减趋势;弹性波在钢筋混凝土传播过程中,高频信号衰减程度大于低频信号,因而低频信号在长距离传播更稳定;波速及振幅在1.0 m处都出现了较大幅度的提高,经分析可知声波在经过混凝土三相交界处时会发生多次折射、反射、吸收衰减等现象,因而离散性增大。可见实际检测过程中的探头布置间距不宜超过1.0 m。

To understand the influence of distance on the propagation of elastic waves,two different sizes of reinforced concrete beams were produced,and the attenuation of elastic waves propagating in reinforced concrete was studied experimentally using the PAC-3 acoustic emission system by simulating the acoustic emission signal through lead break.The results show that the frequency,wave speed and amplitude are all decaying with the increase of propagation distance.Elastic wave propagation in reinforced concrete,high frequency signal attenuation degree is greater than the low frequency signal,so the low frequency signal is more stable in the long distance propagation.Wave speed and amplitude at 1.0 m appears a large increase,after analysis can be seen that the sound waves in the concrete through the three-phase junction will occur a number of refraction,reflection,absorption attenuation and other phenomena.The analysis shows that the sound wave will be refracted,reflected,absorbed and attenuated several times when it passes through the three-phase junction of concrete,thus increasing dispersion.It can be seen that the spacing between the probes should not exceed 1.0 m in the actual testing process.