First Author: SUN Linyuan
Corresponding Author: HUANG Hao
Journal: Journal of Hydraulic Engineering

Abstract

Surface-wave cut-off frequency detection is an effective nondestructive method for determining the depth of concrete surface cracks. At present, the frequency-transmission-coefficient method is commonly used to identify the cut-off frequency; however, this approach is largely affected by the mesostructure of concrete, resulting in limited accuracy.

To improve the precision of cut-off frequency identification, this study proposes a multi-signal phase-shift scattering analysis method. Finite element simulations are carried out to model surface wave propagation and the interaction with mesoscale concrete cracks. Detection mechanisms and identification performance are compared between the traditional frequency-transmission-coefficient method and the proposed multi-signal phase-shift scattering method, leading to the establishment of a more reliable cut-off frequency identification criterion.

Furthermore, the influences of aggregate size, porosity, and detection frequency on the performance of the multi-signal phase-shift scattering method are systematically analyzed. Results show that this method demonstrates superior identification accuracy, and is less affected by mesostructural variations and crack-to-wavelength ratios. Variations in aggregate size, content, and elastic modulus had negligible impact on the method’s ability to detect cut-off frequency effectively. When the surface wavelength-to-thickness ratio exceeds 4.0, the proposed method still achieves robust identification performance.

This study provides a theoretical basis for the quantitative detection of concrete surface crack depth in engineering practice.

Keywords: Concrete surface crack depth; Mesostructure; Cut-off frequency; Frequency-transmission-coefficient method; Phase-shift scattering analysis