Comparison of different damping materials during train vibration at twin tunnels by similarity experiment and DEM

•Scale model and DEM were used to discuss the train vibration reduction effects of SP, CZ and DL.•The CZ absorbs the vibration wave while SP reflects it which are caused by different damping.•The most recommended vibration isolation method in practical engineering is CZ. To reduce the disturbance of train vibration to adjacent tunnels during the operation of near-distance twin tunnels, three reduction methods are proposed. In this paper, the vibration mitigation effects of steel plate (SP), concrete zone (CZ), and double liner (DL) on their tunnels and adjacent tunnels during train vibration are compared by scale model and discrete element method (DEM). The distance between twin tunnels is 0.25 D, where D (6.2 m) is the diameter of the tunnel. The results show that CZ can produce a good vibration isolation effect on the first tunnel (T1) and second tunnel (T2). At the same time, SP has a good vibration isolation effect on the liner and surroundings of T2 but has the potential to increase the dynamic characteristics of T1 surroundings. The vibration mitigation effect of the DL on T1 and T2 is the same, and the ratio of weakening effect is about 30%–50%. In summary, the most recommended vibration isolation method in practical engineering is CZ. This study provides a reference for studying the vibration mitigation effect on adjacent tunnels during operation.