Prediction and efficient control of vibration mitigation using floating slabs: practical application at Athens metro lines 2 and 3

This paper describes the finite element modelling and the in situ evaluation of anti-vibration mitigation measures recently introduced in the latest two extensions on lines 2 and 3 of the Athens Metro: (1) extension of Line 3 from Aigaleo to Haidari and (2) extension of Line 2 from Agios Antonios to Anthoupoli. Appropriate mitigation measures, guaranteeing the allowable ground-borne noise and vibration levels, especially in crossover (CO) locations, were examined, within a noise and vibration study. To do this, the alignment was divided into homogeneous sections, i.e. sections along which the tunnel and soil types, depth and distance from nearby buildings, with particular emphasis on section with COs on direct fixation. Floating slab (FS) track solutions were then evaluated at COs locations ensuring a complete ground-borne vibration attenuation with an insertion loss of - 20 dB V with respect to the predominant excitation (40-125 Hz). The relevant in situ measurement campaign regarding both the dynamic characteristics of FS and the vibration velocity at the relevant receptors proves that the ground-borne noise in the nearest - to FS - buildings at all CO locations was significantly lower than the maximum allowable limits proving the high efficiency of the mitigation measure.