Assessment of Dynamic Vibration Absorbers Efficiency as a Countermeasure for Ground-Borne Vibrations Induced by Train Traffic in Double-Deck Tunnels Using an Energy Flow Criterion

摘要

Double-deck tunnels are an innovative tunnel layout design useful to enhance the efficiency of underground railway transportation systems in which the tunnel is divided into two sections by an interior floor. However, vibration measurements and various recent investigations indicate that train traffic in the upper section of this type of tunnels could induce significantly larger levels of noise and vibration at the nearby residential buildings. This study aims to assess the efficiency of dynamic vibration absorbers (DVAs) as vibration mitigation measures for ground-borne vibrations induced by train traffic in the upper section of a double-deck tunnel. A previously developed semi-analytical model of a track-tunnel-ground system along with a two-dimensional multi-degree-of-freedom rigid body model of the vehicle is employed to compute the vibration energy flow radiated upwards due to a train pass-by. Considering the crucial role of DVA parameters in their efficiency, a global optimisation approach based on a genetic algorithm is used to obtain the optimum parameters of the set of DVAs. The performance of DVAs is assessed for two train speeds taking into account their efficiency in reducing the total vibration energy radiated from the tunnel. The results show more than 6 dB reduction in total radiated energy due to the use of the optimised DVAs.