Study On Vibration Characteristics Of Steel Spring Floating Salb Track For Qingdao Metro Line 3

With the rapid development of the city,the problems of urban traffic congestion have been becoming more and more serious.While metro can play a significant role in reducing the traffic congestion especially after forming the metro networks.However,with the increase of the metro lines,the track vibration and noise caused by trains have affected on people's daily life,health and environment.The steel spring floating slab track system(hereinafter called “FST system”)can effectively reduce the vibration of the metro during operation.In this paper,based on the Qingdao Metro Line 3 from the Yongping Road Station to Qingdao North Railway Station,supported by ANSYS finite element analysis software,establish the finite element analysis model of FST to calculate the modal and steady-state analysis and calculate the natural frequency and vibration attenuation.Compare the differences of vibration characteristics between the normal integrated track beds and FST by testing the stability,ground vibration and vibration isolating system of Qingdao Metro Line 3.Predict and analyze the ground vibration of metros in different tunnel depths by establishing the finite element models of the soil layers and the tunnelsThe main tasks accomplished are described as the following:(1)Based on the design of the FST system for Qingdao Metro Line 3,the finite element analysis models of FST are established to calculate the modal analysis and steady-state analysis.The result shows the natural frequency of FST's model is about 7 to 8Hz,and the insertion loss value of FST has been reduced more than 20 dB within the FST's life span than that of the normal integrated track bed in the frequency range of 4 to 200 Hz when trains passing by.(2)Test the stability of Qingdao Metro Line 3 in normal integrated track bed,low grade and high grade FST bed.The results show the lateral and vertical comfort indexes are less than 2.5 in most of the test time,and it is in excellent condition.(3)Test the ground vibration at different positions from the center line of normal integrated track bed,low grade FST bed and high grade FST bed of Qingdao Metro Line 3.The results show the vibration is very small and the maximum value of Z-vibration and frequency-division level are far smaller than the prescribed limits.(4)Test the vibration of normal integrated track bed and low grade FST and high grade FST with vibration isolating system of Qingdao Metro Line 3,the result show that the insertion loss value of FST is more than 20 dB compared to normal integrated track bed,which prove the FST system have obvious and excellent damping effect.(5)Established the finite element models of tunnels in different depths with ANSYS,and analyze the response of ground vibration under the different depths of tunnel.The results show that the deeper tunnel is,the smaller vibration is,and the vibration attenuation is slow within 35 m from the center line,and fast more than 35 m from the center line and there may be big vibration in some positions during the whole process of vibration attenuation.