Subway-Caused Vibration Propagation Behavior Inside Buildings Above Metro Tunnels

Abstract

This study aims to investigate the vibration propagation behavior inside buildings near metro tunnels. Field measurements were conducted on vertical vibration accelerations of buildings above the Ningbo Rail Transit Line 4, Zhejiang Province, China. A three-dimensional finite element vibration model for the moving train–tunnel–soil–building coupling was established through the numerical model. The impact of the tunnel depth, horizontal distance between the tunnel and building, and the number of building floors on the vertical vibration propagation within the floors was analyzed. Typical field test results indicate that vertical vibration accelerations in the buildings were primarily concentrated in the 50–70 Hz frequency range. The vertical vibration acceleration level (VAL) within the building showed an initial increase and then decrease with the increase of the one-third octave band center frequency. Vibrations in the frequency bands of 40 Hz and above were more dispersed along the floors compared to other frequency bands. The weighted vertical vibration level (VL_Z) fluctuated irregularly with the number of floors. Numerical analysis results showed that changes in tunnel depth and horizontal distance mainly caused attenuation of vertical vibration acceleration levels in the 63 Hz frequency band, with the horizontal distance having a greater impact than tunnel depth. Changes in the number of floors caused significant fluctuations in the vibration acceleration level in the 31.5 Hz frequency band, but did not affect the energy distribution of the one-third octave bands.