Experimental study on interfacial damage characteristics of CRTS II slab track and CA mortar with AE and DIC techniques

Since the interface is often regarded as the weakest part of the ballastless track structure, there is a great need to investigate the interlayer bonding performance to ensure the safety of train op-erations for high-speed railways. In this study, the damage characteristics of the interface be-tween China Railway Track System II (CRTS II) slab track and cement emulsified asphalt (CA) mortar (T-CA interface) under shear loading were thoroughly investigated. The interfacial deformation and damage development process during the direct shear experiments were recorded by a combination of acoustic emission (AE) and digital image correlation (DIC) techniques. Consequently, a bilinear cohesive zone model (CZM) of the T-CA interface was proposed. The results show that the AE activities are rare in the initial stage of loading, while they increase sharply when the shear loading approaches the interface bonding strength. The AE parameters can well characterize the entire process of interfacial failure. Through the DIC technique, the macroscopic deformation process was well captured and the shear stress versus relative displacement curves were derived. Subsequently, the relationship between the shear stress and relative displacement of the interface was well fitted by a bilinear CZM, of which parameters are calibrated through the experimental data. The effectiveness of the proposed bilinear CZM is validated by using a three-dimensional finite element model. This work provides a better un-derstanding for the damage mechanism of the bond performance between CRTS II track slab and CA mortar.