Stiffness and Vibration Reduction Performance of Double-block Floating Slab Track Vibration Isolators

[Objective] To address the shortcomings currently present in high-performance and special vibration-reducing floating slab track systems, such as poor accuracy in maintaining the rail bottom gradient and insufficient construction precision, the CRTS (China railway track system) double-block ballastless track technology is introduced into floating slab track structures, to enhance the stability, smoothness, and safety of advanced and special vibration-reducing urban rail transit track structures, reduce maintenance demands, and improve construction efficiency. [Method] A vertical dynamic coupling model of the vehicle and double-block floating slab track system is established to investigate appropriate stiffness values and layout schemes for vibration isolators. Comparative analyses with monolithic track bed systems are conducted to evaluate the vibration reduction performance and vibration propagation characteristics. [Result & Conclusion] Under two different vibration isolator layout schemes, the stability and safety indicators corresponding to various isolator stiffness values effectively met the required limits. A vibration isolator of stiffness 8 kN/mm with the layout scheme involving alternating spacings of 1.785 m and 1.190 m is proposed. The double-block floating slab track system demonstrate excellent vibration isolation efficiency. When adopting this system, the peak vibration acceleration on the tunnel wall is reduced by 90% compared to that of the track bed. Spectral analysis of tunnel wall vibration acceleration shows that the double-block floating slab track system significantly reduce vertical vibration acceleration across various frequencies, with a maximum Z-vibration level reduction of up to 18.3 dB. At a distance of more than 70 meters vertically above the tunnel center, the environmental vibration levels in urban areas compiled with all regulatory standards.