Influence of the Seam between Slab and CA Mortar of CRTSII Ballastless Track on Vibration Characteristics of Vehicle-Track System

With a lot of application of CRTSII slab ballastless track in China,a series of problems have arises during the slab track service. One of the most typical problems is the seam between the track slab and CA mortar layer, namely CA mortar seam. This may influence the vibration characteristics of the vehicle and CRTSII slab ballastless track. In order to study this phenomenon, according to the actual engineering and based on the finite element, a new vertical vehicle-track coupling dynamic model is established. The model consists of two parts, vehicle element and CRTSII slab ballastless track element. The former is regarded as multi-rigid-body systems, while the latter is established by means of finite element method, in which rail, fastening system, track slab, CA mortar, concrete base and subgrade are considered as a whole body. The rail, slab and the concrete base are simplified as layered Euler beam model. The fastener and subgrade are simplified as the linear spring. In order to consider the characteristics of the CA mortar seam, the nonlinear spring is used to simulate the CA mortar layer. Based on vehicle-track coupling dynamic model, the influence law of CA mortar seam on the safety of vehicle operation, on the displacement and acceleration of each part of the track structures, is revealed, by comparing the dynamics properties of the CRTSII slab ballastless track of the conditions without CA mortar seam and those with CA mortar seam. The result shows that while there is seam between the track slab and the CA mortar layer, it has slight influence on the smooth of vehicle operation, but has significant impact on the mechanical properties of the CRTSII slab ballast-less track structure. The study is expected to provide theoretical guidance for remediation if there are similar problems in the slab track. (C) 2017 The Authors. Published by Elsevier Ltd.