Attenuation properties of ground vibration propagated from subway tunnels in soft ground

Abstract

Ground-borne noise and vibration caused by passing trains in subway tunnels are sometimes perceived in near-by buildings and may pose a problem for residential buildings and facilities requiring silence and freedom from vibration. Field measurements were carried out in this research both in subway tunnels located in the soft ground and on the ground surface at 21 locations in and around the Tokyo area to measure the attenuation property of the ground. The attenuation properties are analyzed for each 1/3 octave band by applying an empirical equation to the measurement results. The material damping coefficient α is obtained for each 1/3 octave band and the relational equation between frequency and material damping coefficient α is proposed. The relational equation enables calculation of the vibration attenuation in the ground with empirical equation considering geometrical and material damping.