Experimental Study on Seismic Performance of CRTS II Slab-Type Ballastless Track Lateral Block of HSRs

The seismic performance of the CRTS II slab ballastless track lateral block (TLB) for high-speed railways (HSRs) is revealed for the first time. Nine test models of the main beam-TLB are constructed with varying quantities and diameters of interface anchorage steel bars. The model scale is 1:2, and the steel scale is 1:4. The study examines the failure mechanism, failure pattern, hysteretic curve, skeleton curve, energy dissipation capacity, ductility, stiffness degradation, and strength degradation of the TLB under low cyclic load. The influence of the diameter and quantity of interface anchorage steel bars on the seismic performance of the TLB is analyzed. The results indicate that the failure pattern of the TLB under low cyclic load can be divided into three stages: (a) the interface of the TLB and main beam initially exhibits minor cracking, which enlarges during loading and closes during unloading; (b) the interface steel bars repeatedly compress the surrounding concrete of the TLB and main beam, and the cracks continue to expand until they penetrate the entire interface, while the interface steel bars undergo shear deformation; (c) the concrete in the interface area between the TLB and main beam is crushed and spalled, and the interface steel bar experiences bending shear deformation, leading to slippage and inclination of the TLB. Increasing the quantity and diameter of interface anchorage steel bars enhances the energy dissipation capacity and ductility of the TLB, reduces the degradation of its strength and stiffness, and improves its seismic capability. However, when the diameter of interface anchorage steel bars reaches 12 mm and the quantity of steel bars reaches 8, the increase rate in energy dissipation capacity and ductility of the TLB slows down while the deterioration rate of strength and stiffness accelerates.