Influence of Train Load on Mechanical Property of Prefabricated Slab Track

To study the influence of passenger and freight trains on the mechanical deterioration of concrete for slab track, the indoor cyclic loading test was conducted and described by using the damage variables based on damage mechanics. First, the FE model consisting of the rail, fastening, slab, CA mortar, roadbed, and subgrade was established. In this model, the reasonable load combination was determined contemplating the equivalent stress levels for the test specimens, as well as the loading frequencies for passing trains. Next, a cyclic loading test for concrete specimens was performed using a MTS loading system. Besides, the dynamic elastic module and the flexural strength for concretes at various loading cycles were calculated with the help of nondestructive testing system. Finally, taking the dynamic elastic modulus and the flexural strength as damage variables, the influences of different stress levels and loading frequencies on the deterioration of mechanical properties for the track slab were obtained. The results reveal that: under passenger or freight train load, the damage of dynamic modulus is about twice that of flexural strength at 2 million loading cycles. Keeping the stress level constant, the damage of dynamic modulus and flexural strength for concrete are greater with the lower loading frequency, especially between 10 Hz and 15 Hz. At a constant loading frequency, the damage of dynamic elastic modulus and flexural strength of concrete accelerates as the stress level increases. Concrete with a stress level of 0.7 is broken after about 1 000 loading cycles. Trains running at a lower speed would fasten the damage accumulation at the beginning of the deterioration process, while trains running at a higher speed would aggravate the consequential damage development.