The environmental problems due to ground-borne vibrations induced by underground railway traffic are an issue of growing concern in urban areas as the demand for underground railway network has been increased. The demand gives rise to the construction of more tunnels, faster trains and use of innovative designs for tunnel structure. Double- deck tunnels are one of these designs in which tunnel is divided into two sections by an interior oor. The aim of this study is to assess the efficiency of dynamic vibration absorbers (DVAs) as vibration mit- igation measures for ground-borne vibrations induced by train pass-by in a double-deck tunnel. A previously developed semi-analytical model of a track-tunnel-ground system along with the two-dimensional multi- degree-of-freedom rigid body model of the vehicle is employed to compute the energy ow radiated upwards due to train pass-by. Considering the crucial role of DVAs parameters in their efficiency, a global optimization approach based on a genetic algorithm (GA) is used to obtain the op- timum parameters of DVAs. The performance of DVAs is assessed for two train speeds taking into account their efficiency in reducing the to- tal radiated energy from the tunnel. The results show more than 6 dB reduction in total radiated energy by the use of optimized DVAs

This work has been carried out in the context of Industrial Doctorates Plan, with the financial support of AV Ingenieros and AGAUR from Generalitat de Catalunya. The authors would like to extend their gratitude to Universi- tat Politècnica de Catalunya (UPC) for its financial support. The second au- thor also wants to acknowledge the funds provided by the NVTRail project, with grant reference POCI-01-0145-FEDER-029577, funded by FEDER funds through COMPETE2020 (Programa Operacional Competitividade e Interna- cionalizaçao (POCI)) and by national funds (PIDDAC) through FCT/MCTES