Application study on fiber optic monitoring and identification of CRTS-II-slab ballastless track debonding on viaduct

China Railway Track System (CRTS)-II-slab ballastless track is a new type of track structure, and its interlayer connection state is considerably important for the operation safety and ride comfort of high-speed trains. However, the location and multiple influencing factors of interlayer debonding lead to difficulties in monitoring and identification. Here, the research on the design and application of a monitoring scheme that facilitates interlayer debonding detection of ballastless track and an effective indicator for debonding identification and assessment is proposed. The results show that on-site monitoring can effectively capture the vibration signals caused by train vibration and interlayer debonding. The features of the data acquired in the situations with and without in-terlayer debonding are compared after instantaneous baseline validation. Some significant features capable of obviously differentiating a debonding state from the normal state are identified. Further-more, a new indicator, combining multiple debonding-sensitive features by similarity-based weights normalizing the initial difference between mutual instantaneous baselines, is developed to support rational and comprehensive assessment quantitatively. The contribution of this study in-cludes the development and application of an interlay-debonding monitoring scheme, the estab-lishment of an effective-feature pool, and the proposal of the similarity-based indicator, thereby laying a good foundation for debonding identification of ballastless track.