Evaluation of interlayer separation state of CRTSII slab ballastless track based on correlation dimension

As a multi-layer structure system, reliable bonding between layers of CRTSII slab ballastless track is the premise to ensure the safety of high-speed train operation. Under the cyclic action of temperature load, the uncoordinated temperature deformation between the track plate and the mortar layer will lead to the occurrence and expansion of interlayer separation. In order to effectively monitor and scientifically evaluate the state of interlayer separation, a key parameter monitoring system for ballastless track was built to monitor the changes of slab temperature and interlayer separation width of ballastless track in service. Based on the chaos theory of nonlinear system, the chaos of time series of slab temperature and separation width were identified. The analysis method of macro micro mapping relationship of interlayer slit state based on correlation dimension was proposed. The research shows that the separation state of longitudinal slab ballastless track is closely related to the slab temperature. When it is near the locked slab temperature, the correlation dimension corresponding to the change time series of separation width is the largest. At the micro level, the propagation of interlayer separation crack can be divided into the cyclic process of crack initiation, propagation and penetration. Combined with the change trend of correlation dimension in different stages, it is suggested that the maintenance threshold is when the separation width reaches 2.0 mm. At the macro level, even if the separation width of ballastless track is the same in different service stages, the hidden gap depth index is quite different due to the continuous deterioration of interlayer bonding quality. Combined with the change of correlation dimension, the actual state of interlayer separation joint can be comprehensively evaluated. The research results can provide reference for the formulation of ballastless track maintenance standards and scientifically guide the line maintenance work. © 2023, Central South University Press. All rights reserved.