Analysis And Evaluation Of Environmental Vibration And Secondary Noise Influencing Factors Along Subway

The rapid development of subways in cities is bringing convenience to people,but at the same time,the around the lines and the indoor secondary structure noise of the buildings along the lines caused by subway are gradually attracting attention.In order to minimise the adverse effects of the subways on the surrounding environment,a great deal of research has been carried out by scholars at home and abroad on issues such as environmental vibrations induced by subway vehicles.In this paper,based on previous research,the dynamic finite element model and acoustic boundary element model are established by numerical simulation.The influence of factors such as track structure and soil properties on the environment vibration around the subway line and the noise from secondary structures in buildings has been studied,and the different situations of the propagation law of vibration and noise are summarized.The main conclusions are as follows:(1)As the distance from the center of the line increases,the overall tendency is for the vibration intensity of the surrounding soil and buildings along the line induced by the subway to gradually decrease,and the indoor noise intensity also decreases.However,soil vibration amplification may occur in some locations,and the form of the track structure has a great influence on the area of vibration amplification and the degree of amplification.(2)Both rubber pads and steel spring floating slabs can effectively reduce the high frequency vibrations of the soil as well as the building floor slabs and the noise intensity of the building interior secondary structure.However,due to the self-excitation of the track structure itself,the low frequency environment vibration below 30 Hz may be greater.(3)The softer the soil layer,the weaker the vibration intensity of the soil in the low and medium frequency range,but for the vibrations above 80 Hz,the vibration intensity of hard soil farther away from the line center will be greater.At the same time,in the case of gay love of soft soil road,the vibration intensity of building floor and indoor noise intensity in the middle and low frequency range are stronger than that of hard soil roadbed;while in the medium and high frequency range,it will be weaker than in hard soil roadbeds.(4)The low frequency vibration of the building floor at 4Hz does not basically change as the building height rises.However,above 10 Hz,the vibration intensity of the building decreases with increasing height for normal bolster track and rubber mat floating slab track,while for steel spring floating slab track,the vibration intensity at the middle floors may increase.Moreover,in the case of three kinds of track structures,the indoor loudest noise intensity at each floor of the building decreases with increasing floor height.(5)The effect of the vehicle system on the vibration strength of the soil and buildings is not significant.(6)The intensity of indoor secondary noise shows a distribution pattern of weakening from the surrounding walls to the center,and the form of the track structure has a significant effect on the distribution pattern of the noise in frequency,while factors such as floor height,distance from the center of the line and the nature of the soil do not affect the distribution pattern of the noise.