MECHANISM OF INTERFACIAL SHEAR FAILURE BETWEEN CRTSⅡ SLAB AND CA MORTAR UNDER TEMPERATURE LOADING

Interfacial shear failure and large longitudinal displacement of track may occur under temperature load, once the longitudinal continuity of CRTS II slab track is broken. The complex interaction relationship between slab and CA mortar under temperature loading is kind of “bonding-debonding-contact”, which can be simulated by surface based cohesive zone model (SCZM). A three-dimensional finite element model of interfacial shear failure of CRTS II slab track was established, and the model was validated by the results of the longitudinal shear test of slab track. Interfacial shear failure process and influence law of parameters such as shear strength, shear stiffness and fracture toughness were analyzed particularly. The study shows that interfacial shear stress at slab end where the slab is unconnected is the largest, and it gradually decays with the increase of the distance to the slab end. The interfacial shear stress at slab end reaches shear strength firstly, and interface damage initiates under 4.2 temperature rising. When the increasing ℃ extent of temperature is 10.5℃, the interfacial shear stress at slab end decays to zero and interfacial crack expands quickly. Excessive shear stiffness and small shear strength lead to the initiation of interface damage easily. Improving interfacial fracture toughness and shear strength can effectively control interfacial crack and improve the longitudinal stability of track.