PREDICTION ON VIBRATION ACCELERATION OF THE ENVIRONMENT INDUCED BY FUZHOU METRO

A two subsystem model, consisting of a vehicle-track coupled model of vertical vibration and the tunnel-soil model of 3D FEM are established, typical distribution of soil along the metro lines is summarized, and the vibration accelerations of the environment are predicted using the tunnel-soil model, with the accelerations of the vibration source obtained from the vehicle-track coupled model. The results show that the two main site classifications in Fuzhou are Class II and III as defined in the Code for Seismic Design of Buildings (GB50011-2010), the vibration acceleration level of the environment induced by Fuzhou metro attenuates with the distance to the centre line of track, and the low-frequency parts of the Class III site experience greater vibration than those of the site of Class II, which can arouse buildings or precision instruments with similar frequency resonance anomalies. Additionally, there is an amplified zone in each site class, and that is more diffuse in Class III sites. To the extent that the vibration acceleration frequency of the environment embodies the resonance frequency of fasteners and track, the distance has an inconspicuous effect on acceleration frequency and low-frequencies at about 2Hz and below; with increased train speed, the vibration acceleration in the environment increases obviously, while metro load capacity only slightly increases vibration accelerations within a certain distance. The vibration acceleration of the environment under a train running in single line is much less than under trains running in double line, and the vibration of the of Class III sites is expected to fall more steeply than those of the Class II sites.