Analysis of the shear failure between track slab and CA mortar layer caused by thermal effect for ballastless track

Shear failure between track slab and CA mortar layer in the ballastless track induced by extreme temperature conditions threaten the operation safety of high-speed trains. The shear failure is closely related to the thermal damage of CA mortar. Series of compression tests under different temperature were conducted on CA mortar to investigate degradation of mechanical characteristic of the CA mortar induced by temperature. The tests results indicated that both elastic modulus and peak stress of the CA mortar decreased linearly with increasing temperature. An damage model was proposed to accurately describe the degradation of mechanical characteristic of the CA mortar. Furthermore, the proposed model was used to investigate the shear failure between track slab and CA mortar layer induced by extreme temperature conditions. The results indicate that the thermal damage to CA mortar can cause clear increase of the shear stress between CA mortar layer and track slab. The shear failure between CA mortar layer and track slab is most likely to occur under overall temperature rise combined with negative temperature gradient, which often occurs during cool summer nights in mid-latitude areas in China.