2D Dynamic Response of Floating Slab Track-Tunnel-Ground Model Under Moving Harmonic Load

A two-dimensional (2D) floating slab track-tunnel-ground coupled model was adopted to analyze the vibration characteristics of floating slab track in the metro tunnel.By introducing displacement potential functions and using double Fourier transformations,response solution of the 2D model under moving harmonic load was derived.It indicates that there are three resonant frequencies in the 2D model,the ground displacement response mainly concentrates in the low frequencies,with a peak value frequency around 1Hz,and the changes of vertical ground displacement under different load frequencies are different.The ground acceleration response mainly concentrates in the middle and low frequencies and reaches its maximum value at the second resonant frequency.Adopting the floating slab track is unable to reduce the ground displacement but is effective to reduce the ground acceleration response in which the load frequency is above 1.414 times of the second resonant frequency.Increasing the floating slab mass and decreasing the steel spring stiffness are able to reduce the ground acceleration response and realize the vibration attenuation goal while the ground acceleration is trivially affected by changing stiffness of the rail pad or floating slab.The present research can provide reference to a quick evaluation for the train-induced environmental vibration.