| Currently,the development of subways in China is among the top ranks in the world.However,while subways bring prosperity to the city and convenience to the people,the vibration and noise issues they cause have also received widespread attention.There are also increasing complaints from residents along the subway line about vibration and noise caused by subway operations.Based on previous research,a 3D finite element model of track-tunnelsoil-building and an acoustic boundary element model for buildings were established by combining FEM and BEM.On the premise of verifying the correctness of the model in comparison with the measured data,the characteristics and propagation laws of building vibration and secondary radiated noise were investigated.Then,this paper provided recommendations for vibration reduction and noise control.The main works and results are as follows.(1)Summaries were made on the main methods of predicting environmental vibration and secondary radiated noise caused by subways and the current status of research on influencing factors at home and abroad.(2)Using the vehicle-track coupled dynamic theory,the vertical time-domain wheel-track forces were computed through programming.A 3D finite element model of track-tunnel-soilbuilding was established in the finite element software Ansys.The vibration response of the building was obtained with the train vertical time-domain wheel-track force as the excitation.And the paper focused on analyzing the vibration characteristics and laws of the building under the changes of vehicle speed,tunnel depth,subway train type and floor.(3)The acoustic model was established in the acoustic software Virtual.Lab.Then,the building’s vibration response obtained through Ansys was used as the acoustic boundary condition to calculate the building’s acoustic radiation characteristics.Furthermore,the changes and laws of the secondary radiated noise of the building at different vehicle speeds,tunnel depths,subway train types and floors were analyzed.The noise reduction effect of soundabsorbing materials on the building was also explored.At the same time,the secondary radiated noise was evaluated for the rooms under the calculation conditions of this paper,and the noise reduction treatment was carried out for the rooms exceeding the standard.The study shows that the maximum peaks of the 1/3 octave spectrum of vibration acceleration levels in the four-story building studied in this paper mainly occur at 63 Hz and80Hz,and with the increase of the floor,the vibration decreases first and then increases.The vibration of each layer of the building increases with the increase of vehicle speed,and increases with the change of subway train type from B to A.In addition,the vibration of each layer of the building decreases with the increase of tunnel depth.In both horizontal and vertical directions,the indoor sound pressure level of the building shows symmetrical distribution.Under the changes of vehicle speed,tunnel depth and subway train type,the trend of the sound pressure level in each plane of the room is consistent with the change of frequency in each working condition.Changing the sound absorption property of the building can effectively reduce noise levels in rooms,especially in the frequency range larger than 40 Hz. |
