PREDICTION OF VIBRATIONS IN THE TUNNEL AND FREE FIELD DUE TO PASSAGE OF METRO TRAINS

A method is presented to calculate the metro-train-induced vibrations in the tunnel and free field. Based on the analytical solution of dynamic response excited by the moving loads in the tunnel and free field, the vibrations induced by the passage of metro trains can be calculated if the transfer function in the frequency- wavenumber domain and the moving axle loads in the frequency domain can be obtained. The transfer function is calculated using the three-dimensional coupled periodic finite element-boundary element model in the frequency- wavenumber domain, and the moving axle loads are considered as the contact force between wheel and rail due to the rail unevenness. The response in the tunnel and free field north of East Gate of Peking University station on line 4 of Beijing metro is predicted, and the vibration mitigation efficiency of a floating slab track is studied and compared with a general slab track. The results show that the method has good applicability and the floating slab track is an effective vibration reduction measure, but not effective for the vibrations at low frequencies.