Detection of mortar defects in ballastless tracks of high-speed railway using transient elastic wave method

Abstract

In the multi-layered track structure, the defects of cement-emulsified asphalt (CA) mortar are hidden and difficult to detect. There is still no effective detection method yet. Thus, this paper discusses the feasibility of mortar defect detection by transient elastic wave method. First, a finite-element model (FEM) was created by the LS-DYNA for a section of the multi-layered structure of the ballastless tracks, and the features of elastic waves were investigated in ballastless tracks with and without defects. Then, three identification parameters were presented and the spectra of measuring points were analysed in detail. Moreover, the IE method was adopted to detect the defects in the entity models of ballastless tracks. It is shown that the internal defects of the mortar layer can be pinpointed by comparing the waveforms of various frequencies in the frequency domain, different peaks of resonance frequency, and diverse power density values.