Study on detection of concrete surface crack depth using surface wave method at a meso-scale
Detecting the depth of concrete surface cracks based on the R-wave cutoff frequency is an effective non-destructive testing method.Currently,the frequency transmission ratio method is commonly used to identify the cutoff frequency;however,this method is greatly affected by the concrete's meso-structure,leading to suboptimal identification results.To enhance the accuracy of cutoff frequency identification,this paper proposes the multi-channel signal phase shift dispersion analysis method.Finite element simulations were conducted to detect the depth of surface cracks in uniform media and concrete meso-models using R-waves.The detection mechanisms and iden-tification effects of the frequency transmission ratio method and the multi-channel signal phase shift dispersion anal-ysis method were compared and studied.Standards for identifying the cutoff frequency were provided,and the effects of aggregate size,porosity,and detection frequency on the multi-channel signal phase shift dispersion anal-ysis method were analyzed.The research results indicate that the multi-channel signal phase shift dispersion analy-sis method has better identification effects and is not affected by the meso-structure and the crack thickness ratio.Changes in aggregate size,content,and elastic modulus basically do not affect the method's effective identification of the cutoff frequency.When the R-wave wavelength is less than the thickness of the component and the porosity does not exceed 4％,the method still exhibits good identification effects.This study can provide a theoretical basis for the quantitative detection of concrete surface crack depth in practical engineering.
concrete surface crack depthmeso-structurecutoff frequencyfrequency transmission ratio methoddispersion analysis of phase shift method
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