Metaconcrete-filled steel tubular column for rail-induced vibration mitigation in tunnels

Abstract

Ground-borne vibration induced by subway trains in urban areas has caused disturbance to inhabitants along subway lines. Its effective reduction, therefore, has become increasingly important and has attracted more and more attention. Metamaterial/metastructure-based approaches with excellent vibration attenuation capabilities have been recently proposed to mitigate train-induced vibrations around rail tracks. However, owing to the intrinsic difficulties of conventional metastructure designs, effectively mitigating the low-frequency components of train-induced vibrations by installing metastructures around train tracks remains a great challenge. In this study, an innovative design with metaconcrete-filled steel tubular column (MFSTC) is proposed to replace conventional concrete subgrades under rail tracks. The performance of the MFSTC in reducing low-frequency vibrations is first investigated analytically and numerically. It is found that the reduction of the low-frequency vibrations starting near 0 Hz is achievable with proper design of the bottom support of the MFSTC and the shear resistance between the concrete matrix and steel tube of the MFSTC. In addition, the effects of bottom support stiffness and MFSTC configurations on the MFSTC’s vibration reduction capacities are examined. The results show that high shear stiffness between the steel tube and concrete matrix and strong bottom support to the outer steel tube can effectively suppress low-frequency vibrations. A detailed design strategy of the MFSTC aimed at attenuating train vibrations is proposed, and its capability is demonstrated in a case study.