Mechanism of rail corrugation formation on metro curves with a type of floating-slab track

A steel spring floating-slab track (SSFST) capable of mitigating railway-induced vibrations has been widely used in a metro line in Beijing. In sharp curves with radii of less than 500 m, severe corrugation with wavelengths of about 125–200 mm and passing frequencies of 70–80 Hz occurred on low rails. Field measurements and numerical simulations were used to investigate the cause of the corrugation. The results show that the wavelength of corrugation is related to the speed of the vehicle and the corrugation passing frequency is a fixed frequency. The formation of the rail corrugation in the sharp curves does not depend on the torsional and bending resonances of wheelsets and P2 resonance. The wheel–rail vertical fluctuating force at frequencies of 67–75 Hz arises easily under a broadband excitation of the rail irregularity due to the vertical bending of the rail and the floating slab relative to the subgrade. The numerical simulations show that the corrugation with dominant wavelengths of 160–200 mm initiates when the vehicle passes over the irregularity. The simulation results are consistent with the field test results. The corrugation occurs on SSFST as a result of the vertical bending of the entire track, driven by a wavelength-fixing mechanism.