New approach for Characterization of Interfaces of Ballastless Railway Tracks Based on Ultrasonic Echo Principles

摘要

This paper presents the progress of the location of delaminations using ultrasonic imaging in the interface of a 3-layer model, which simulates ballastless railway tracks. The data is acquired by point contact shear wave devices. The evaluation software is based on the interactive 3D reconstruction calculation program Inter-SAFT. A new approach was tested applying a three layer system which is bonded using a coupling agent for shear waves. This system has similar acoustic properties when compared to real railway tracks. Hence, the experimental conditions may principally stay the same with only a slight adaptation being required when applied to a real track. Several samples were investigated experimentally to figure out the specific features of each concrete layer, the coupling material, and the applicability of the inspection approach to a two and three layer system. Due to the different sound velocities in the different layers a 2D and 3D reconstruction with velocity correction using Inter-SAFT was used to indicate the depth and the size of artificial defects. This will additionally require time reversed reconstruction principles to be applied.