Influence Of Steel Spring Failure Of Floating Slab Track On Vibration Characteristics Of Infrastructure

With the rapid development of economy and the acceleration of urbanization,metro traffic in China has made great progress,and steel spring floating slab track has been widely used in metro traffic for its excellent vibration isolation performance.Under repeated train loads,the steel spring will loses its efficacy unavoidably,which may have a bad effect on the infrastructure.Therefore,it is necessary to make a profound study on the influence of steel spring failure of floating slab track on vibration characteristics of infrastructure to provide sustains for the application of floating slab track in metro traffic.The vertical coupled dynamics model for the metro and the floating slab track was established based on the vehicle-track coupled dynamics.The steel springs forces and the rails vibration were obtained.The reaction forces of the steel springs were applied to the three-dimensional finite element transient dynamic analysis model of the tunnel and soil.The influence of steel spring failure of floating slab track on vibration characteristics of infrastructure was investigated.The results showed that the ground acceleration decreases rapidly with the increase of the distance from the center line.The local rebound occurred in a small range of 12-30 m,and the acceleration reached its peak at the place about 20 m away from the center line.The main frequency of acceleration of rail,tunnel base and tunnel wall is 8.63 Hz,which is close to the natural frequency of floating slab.The vibration attenuated quickly in soil,and the high frequency componments attenuated quickly than the low ones.The reaction forces of the multiple steel springs adjacent to the failure will increase in varying degrees,the steel springs forces adjacent to the failure increasing by 91.44%,74.54% and 58.14% respectively when three pairs of steel springs at the end of slab fail continuously.The acceleration of track base,tunnel wall and ground increases quickly with the increase of the failure number of steel springs at the end of the slab,but the acceleration decreases with the increase of the failure number of steel springs in the middle of the slab.The steel springs failure at the end of the slab has a greater effect on the displacements of the rail,the reaction forces of the steel springs,the acceleration of the tunnel wall and the ground than the steel springs failure in the middle of the slab.When three pairs of steel springs at the end of slab fail continuously,the rail displacement,the reaction forces of the steel springs,the acceleration of the tunnel wall and the ground near the failure position increase by 88.04%,91.44%,291.72% and 253.90%,respectively,which increasing by 35.63%,39.29%,24.60% and-12.74%,respectively,when three pairs of steel springs in the middle of slab fail continuously.The failure of the steel springs at the end of the slab led to the increase of the ground acceleration,the failure of the steel springs in the middle of the slab led to the decrease of the ground acceleration,but the failure of the steel springs in the quarter of the slab have little effect on the ground acceleration.When a pair of steel springs fail at the end of slab,in the middle of slab and in the quarter of the slab,the ground acceleration at the failure section increases by 50.28%,-3.68% and-0.61%,respectively.The ground displacements and the main frequency of the acceleration of tunnel base,tunnel wall and ground were little influenced by the failure of the steel springs.