Ballastless Track Bed Slab Layer Damage Identification Based On Modal Parameters

Slab ballastless track is the multilayered track structure,in which the CA mortar layer provides the necessary flexibility for the whole track structure to ensure Deformation compatibility between the layer and the layer under train load.In long service,the interlayer gap appears slowly between the mortar layer and the support layer of the slab or the track slab under the common effect of water,temperature and train load,then the CA mortar layer void gradually formed,which seriously affects the stability of track structures.At present,there are many researches on the dynamic characteristics of the ballastless track structures under damage state,and the method of identifying the damage of the track is mostly based on the method of media detection.Based on the modal theory,the sensibility of different modal parameters about the track structure is researched to identify the ballastless track structure layer void and find the advantages and disadvantages of different modal parameters,then identification of different model parameters on the damage location and scope is proved by combining with the vibration test analysis software and the simulation test.(1)Based on the previous research results of concrete structure damage detection,methods of application to structural damage identification are classified and summarized,while combining with the characteristics of ballastless track structure,current ballastless track structure of rail damage detection methods are summarized.Greatly analyze the advantages and disadvantages of structural damage identification methods based on modal parameters.(2)By setting the mortar layer in different lengths and different ranges in the CRTS II slab ballastless track,The modal shape,modal curvature and strain mode data of different structures are obtained by modal analysis.The sensitivity of the modal parameters to the cavitation damage is obtained by comparing the ability of the modal parameters to the damage position and range(3)In the hammering simulation experiment,noise effect of different degree is set.The modal parameters of the track structure are obtained by analyzing the acceleration signal of the measuring pointand the noise sensitivity is obtained by analyzing the anti-noise ability.At the same time,the structural modal parameters obtained from the measured points under different void damage conditions are used to verify the effect of the damage position and range.