Evaluation of condition of gravel ballast layer on high-speed railway using surface wave method based on harmonic wavelet analysis of waves

In this research, a surface wave method based on harmonic wavelet analysis of waves was proposed to determine the condition of a gravel ballast layer in a railway as indicated by its shear wave velocity. To show the feasibility of the proposed method, a numerical simulation was performed, and the method was applied to determine the one-dimensional shear wave velocity profiles and two-dimensional shear wave velocity maps of a gravel ballast layer along the railway track direction in the field. The numerical simulation and field applications demonstrated the promising potential of the proposed method.