Ambient Vibration of Underground Structures Induced by Adjacent Subway Operation

Abstract

Vibrations from subway operations can negatively affect adjacent underground spaces. This study, based on a loess site, employs a two-stage numerical method to analyze the vibration responses of the track, tunnel, site, and nearby two-layer frame underground structures during subway operation. The vibration propagation and the response patterns of the underground structure are examined. Results indicate that vibration propagates through four stages—“track-tunnel-site-underground structure”—with intensity gradually decreasing during propagation. The track system mainly attenuates high-frequency components above 120 Hz, while the loess site absorbs frequencies above 65 Hz. The spatial distribution and spectral characteristics of the underground structure vibrations correspond to their vibration modes and frequencies. Vibrations near the natural frequencies of the structure may be amplified. The ambient vibration intensity on the middle floor of the two-layer underground structure is higher than on the bottom floor. As the distance from the subway line increases, the ambient vibration intensity decreases, but the spectral characteristics remain unchanged. Under the study conditions, the ambient vibration exceeds the limit value. Ambient vibration in specific areas can be mitigated by altering the structure’s natural vibration characteristics or by blocking vibration propagation. The natural vibration characteristics of the underground structure can guide the functional layout of the interior space. Areas sensitive to ambient vibration should be located in regions with weaker natural vibration.