Author(s): Zafiropoulou Vassiliki, Vogiatzis Konstantinos, Mouzakis Haralampos
Attiko Metro S.A., in view of the further development of the Athens Metro network, has fully initiated the new extension of 7.6 km, for line 3 “Haidari to Piraeus Dimotiko Theatre” towards “University of Piraeus” (forestation), connecting the major Piraeus Port with “Eleftherios Venizelos” International Airport. During the operation of this major urban subway rail transit system, vibrations are expected to be generated when transmitted through the soil and cause vibrations in nearby buildings. In urban areas, these vibrations are a consequence of the vehicle forces acting from the wheels onto the track in local defects. The transmission of ground-borne vibrations from subway rail transit systems in a building is mainly governed by the transfer function (TF) of vibration diffusion from the tunnel wall or invert towards the soil surface in the façade of the given protected building. Therefore at the early stages of a vibration assessment, it is necessary to complete a rigorous and detailed analysis in the basis of a detailed finite element calculation. During the construction of the extension of Athens Metro to Piraeus a methodology was proposed and already tested in situ in order to determine the necessary TF of the rail vibration diffusion inside the given geological media demonstrating the vibration attenuation values in 1/3 octave band analysis. This paper presents the metrological methodology of the relevant measurements campaign and analyses the findings in several sections of the TBM tunnel using as a linear source the TBM muck train and ensuring simultaneous recordings both in tunnel wall and the soil surface. This metrological approach is very important in order to ensure a high accurate estimation of the expected vibration and ground borne noise levels in the façade of each receptor, during operation, and assess possible negative effects on local communities from the metropolitan railway–induced ground vibrations.
Name: Prof KONSTANTINOS VOGIATZIS