The Study On Crack Initiation And Propagation Of CRTS? Slab

Ballastless track has played a more and more important role in ensuring the high speed,riding comfort,and safety of high-speed trains.China Railway Track System(CRTS)type II ballastless slab track is one of the main forms of widely applied slab tracks around china.Concrete and reinforced concrete are very commonly used in CRTS? slab tracks.Thus,concrete cracking is inevitable one main trouble with its low tensile strength,especially when exposed to harsh natural environment and long-term train-induced dynamic load.Though pre-splitting crack on the slab has just been designed to prevent cracking,many other types of cracks still have developed in the position where not allowed in the original design through high-speed train operation investigation.The cracks or voids between layers of CRTS? slab tracks could cause the structure performance degradation,bearing capacity decline and even endanger the train working.This research mainly focus on the CRTS? track slab,ranging from the three-dimensional finite element model to the two-dimensional discrete element model of typical section,including several aspects as follows:(1)Based on the literature research,the patterns and reasons of ballastless track cracking are researched and studied.(2)A three-dimensional finite element model(FEM)of CRTS? slab track on elastic railway subgrade is built up based on finite element theory and the smeared crack models.The location and path of cracks of CRTS ? slab track are studied under the vertical load of train and the different width voids between the track slab and the substructure,temperature gradient load,the combined train load and voids.At the same time,the track slab's warping displacement and the tensile stress of elastic foundation under the the vertical load of train and the different width voids were studied.(3)A two-dimensional discrete element model of CRTS? slab track section is established based on the discrete crack model according to the results above.The width and length of the crack under train load are studied.