Environmental vibration prediction and evaluation method based on vehicle-track-tunnel system and key parameters impact

In response to the environmental vibration caused by subway cars accompanying the increasingly dense urban subway network, based on the spatially coupled time-varying dynamics model of vehicle-track-tunnel, this paper introduced the empirical prediction formula of environmental impact assessment. And it developed an efficient method for predicting and evaluating vehicle-induced environmental vibration. The influence of key parameters including vehicle speed, fastener stiffness damping and cushion stiffness damping on tunnel wall frequency division vibration level and ground Z vibration level was studied. The results show that with the increase of vehicle speed, the amplitude of the spectrum increases, the peak frequency shifts to the high frequency, the Z-vibration level of the tunnel wall firstly increases, and then decreases because the peak frequency shifts out of the weight range. When selecting fastener parameters, it is necessary to take into account the influence of driving performance and environmental vibration. The damping effect is not obvious when the fastener stiffness exceeds 60 kN/mm. The cushion pad has more significant influence on tunnel wall vibration than the fasteners. The damping of fastener should be selected below 26 (kN∙s)/m to meet the limit requirements. The driving smoothness is not affected by the fastener parameters. When damping is less than 600 (kN∙s)/m³, the Z vibration level of the tunnel wall increases with the increase of the stiffness and damping of cushion pad, and the Z vibration level of the tunnel wall reaches the maximum value at the frequency of 20 Hz and the damping of 600 (kN∙s)/m³. In addition, the standard range of different types of buildings from the center of the line is given based on the specification. When the design speed is or below 80 km/h, the residential and educational buildings should be further than 20 m from the center of the subway line. The commercial and industrial buildings should be further than 10 m from the center of the subway line. 20～1 000 (kN ∙ s)/m³ damping pad and 5～24 Hz vibration isolation frequency corresponding to the indoor vibration level can meet the requirements of commercial and industrial buildings, using more than 600 (kN∙s)/m³ damping requires residential and educational buildings further than 10 m from the line center. The research results can provide reference for the design of vibration damping for subway line and structures.