Abstract: Firstly,the failure mode and adhesive mechanism of interface between different layers of ballastless track were analyzed by simplifying temperature load into the shear load of track slab.Then,on the basis of constructive cohesive force model and experimental bond strength parameters of cement asphalt mortar,an interface finite ele- ment model of ballastless track structure was established.Finally,the evolution rules of interfacial stress,interfa- cial bond bearing capacity,interfacial relative displacement and interfacial cracks under the action of shear load were investigated.The results show that (1) both interfacial shear stress and normal stress distribute unevenly and achieve their maximums at the ends of track slab,and interfacial normal stress may result in a tension of track slab at two ends of the slab; (2) under the action of shear load,the interface fails gradually as a result of the interfacial shear stress exceeding the maximum bond strength,and the maximum interfacial bond bearing capacity is 264.8kN; (3) the longitudinal displacement of track slab relatively to mortar-filling layer increases continuously with the shear load and then longitudinal cracks appear; and (4) the relative vertical opening displacement decreases after the in- terface has been cracked,followed with an interfacial shear fracture which may result in the delamination of ballast- less tracks.

Key words: ballastless track, shear load, interface, crack, failure, finite element model, bond strength, relative displacement