Fatigue Testing of CRTS Ⅲ Ballastless Slab Track Structures under Transverse Bending

To investigate the transverse mechanical performance of CRTS Ⅲ slab ballastless track structures under the cyclic action of train loads, a full-scale CRTS Ⅲ slab track structure was fabricated using the same materials and technology as that employed in practical on-site construction applications. Six slab track specimens with one or two sleepers were fabricated from the full-scale slab track structure. Fatigue tests under transverse bending were conducted on these slab track specimens supported on rubber plate-simulated subgrades. The characteristics of stress distribution, deformation distribution, and nature of development of fatigue damage on slab tracks subjected to transverse bending were determined from the fatigue tests. The fatigue test results indicated that longitudinal cracks first appear on the top surface of the track slab in the middle of the slab track specimens with one or two sleepers under fatigue cycles of 15.0-255.0 kN and 42.5-425.0 kN, respectively. Several splitting cracks subsequently developed from the transverse prestressing tendon to the top surface of the track slab on the profile of anchorage end. After cumulative 5 million fatigue cycles, the loads for a composite plate with a track slab-infilling layer under the three-point bending mode corresponding to self-compacting concrete (SCC) cracking and interlayer bond-slip reduced by 20%-30% and more than 25%, respectively. It can be concluded that fatigue damage and interlayer delamination have adverse effects on the cooperative working performance of the track slab and the SCC infilling layer.