Calculation of dispersion curve by combined cross-spectrum and phase shift method and its application to evaluate compactness of subgrade

It is important to evaluate the compactness of subgrade of expressway, which greatly affects the travelling safety on the expressway. It is advantageous for Rayleigh Wave to detect the compactness of the subgrade rapidly, continuously and nondestructively. It can restrict phase velocity using the phase-shift method in the calculation of frequency dispersion curve with cross-spectrum method. The algorithm can overcomes the failure to calculate the phase velocity using the cross-spectrum method in low frequency especially. The calculation of theoretical model indicates that the combination of these two methods can improve the detection precision transversally and vertically. It will be helpful for obtaining relatively better effects in the detection of the compactness of the subgrade of the expressway.