Study On Effect Of Steel Spring Floating Slab Track On Metro Induced Environmental Vibration

Metro traffic is developing rapidly in China, which brings more and more environmental vibration problems. As a track structure which has excellent effect on reducing the vibration, floating slab track has been widely used in underground traffic. It is nessensery to study the vibration mechanism of floating slab track to provide sustains for the application of floating slab track in metro traffic.The research status of environment vibration caused by metro traffic and vibration mitigation mechanism of floating slab track are reviewed and summarized. The influence of steel spring floating slab track on the environmental vibration is investigated by FEM (Finite Element Method) and vehicle-track coupled dynamics theory.A three-dimensional finite element model of steel spring floating slab track is established by ANSYS. Based on vehicle-track coupled dynamics theory, a vertical vehicle-floating slab track coupled model is set up and the characteristic of floating slab spring force is analyzed. The results indicate that the frequency components of the spring force are directly related to system parameters, speed of vehicle and natural frequency of floating slab track. Frequency components mainly concentrate nearby the speed/vehicle length ratio, its integer multiples and the first order natural frequency of floating slab track.A three-dimensional finite element model of tunnel structure-soil is established by ANSYS, and transient response is cauculated using floating slab spring force as input excitation. The results show that the frequency components of ground acceleration mainly concentrate nearby the first order natural frequency of floating slab track. With increase of the distance from the centerline, the ground acceleration amplitude minishes, and attenuation of high frequency vibration is faster than the low frequency vibration.Taking a co-constructed structure of a metro tunnel and a building as an example, a three-dimensional finite element model is built by ANSYS, transient response is cauculated using floating slab spring force as input excitation in the same way. The results indicate that the vibration mitigation of floating slab track is not improved with the reduction of first-order natural frequency. A resonance phenomenon is found in the co-constructed structure when the first-order natural frequency of floating slab track is 6Hz. If the first-order natural frequency departures from 6Hz through adjusting the structural parameters of floating slab track, the resonance will be avoided, and the vibration amplitude will be minished.