| With the development of subway construction,the impact of subway train vibration on the surrounding environment has become one of the hot issues currently studied.Shijiazhuang Metro has received complaints from residents about excessive train operation noise.Therefore,grasping the law of train vibration propagation and the impact of key factors in Shijiazhuang Metro has become an urgent problem to be solved.Based on the actual soil parameters in Shijiazhuang area,the paper uses finite element analysis software to establish a track-tunnel-soil three-dimensional finite element numerical model and conducts load time history analysis,and analyzes the time domain and frequency domain propagation law of subway vibration in the surrounding site and the impact of key parameters,Combined with the limits specified in my country’s"Urban Area Environmental Vibration Standard"(GB10070-88),the vibration and noise evaluation and comparison were carried out,and the attenuation effect of steel spring floating slab track beds on ground vibration response was discussed.The main conclusions are as follows:(1)The peak acceleration of the ground surface vibration pick-up point within50 m from the tunnel centerline is between 0.0135 m/s~2and 0.0621 m/s~2,and as the distance increases,the peak acceleration and the effective value gradually decrease.The dominant frequency is concentrated between 35 Hz and 75 Hz,and the peak value is around 50 Hz;the maximum Z vibration level variation range is 61.69 d B to72.01 d B.(2)The response intensity within 50 m of the ground surface caused by the operation of the Type B vehicle is slightly smaller than that of the Type A vehicle,and the vibration acceleration level attenuation in the time domain is between 0 d B and 2 d B.The difference in the frequency domain vibration acceleration levels of the two models on the ground is mainly reflected in the low frequency range of 0 Hz to 10 Hz.The maximum Z vibration level of the B model is reduced by about 1 d B compared with the A model.(3)The change of subway operating speed has a significant impact on the vibration response of the ground surface.The lower the speed,the slower the vibration decay rate and the smoother the curve.When operating at a speed of 50km/h and 20 km/h,the vibration acceleration level at the surface above the center line of the tunnel is reduced by 5.95 d B and 5.67 d B relative to 80 km/h.The speed limit can reduce the impact of noise pollution on sensitive environments influences.(4)When the train is running on a single line,the vibration intensity generated is less than when the train is running on two lines,but the vibration attenuation law is basically the same as that of the two lines.(5)With the increase of buried depth,the intensity of surface vibration in the time domain gradually weakens.When the buried depth is greater than 15 m,the attenuation effect of ground vibration and noise decreases.(6)The vibration response of the ground surface is directly related to the dynamic elastic modulus of the soil around the tunnel.The larger the dynamic elastic modulus,the faster the attenuation rate.The impact of subway vibration and noise on the ground can be reduced by choosing the way to penetrate the harder soil layer.Impact.(7)The damping effect of steel spring floating slab track bed in low frequency range is worse than that of medium and high frequency.Above 25 Hz,the maximum Z vibration level of the steel spring floating slab track bed is significantly reduced compared to the ordinary track bed,which effectively controls the impact of vibration and noise.Therefore,the steel spring floating slab track bed can be used to reduce vibration when necessary. |
