Research On Measurement Of Environmental Vibration Of Subway And Effect Of Damping Measures

In order to improve the increasingly congested urban traffic problems,subway has been vigorously promoted in major cities with the advantages of making full use of urban space resources and low-carbon environmental protection,but it has brought a lot of convenience to people but also induced environmental vibration and other problems.Vibration reduction has become a necessary technical measure in subway construction.Based on the field measurement of the vibration reduction measures of the subway,the paper also carries out the numerical analysis of the track structure of the ordinary track bed,the elastic short sleeper and the pioneer fastener.The numerical analysis of track structure combined with vanguard fastener and elastic short sleeper and the track structure of new H-type vibration absorption measures are carried out to study the damping effect of various kinds of vibration absorption measures,mainly including:(1)The vibration reduction measures of elastic short sleeper,steel spring floating plate,pioneer fastener,rubber floating plate and double layer nonlinear fastener are studied in the field.The vibration level is 1/3 times frequency range,Compared with the relative damping effect of the vibration reduction measures under the same line,the spectrum index shows that the relative elastic short sleeper of the steel spring floating plate has the effect of 23.2dB,the double layer nonlinear fastener is relative to the pioneer fastener,and the rubber floating plate has the damping effect of 1.6 dB and 2 dB respectively.Elastic short sleeper,vanguard fastener and double layer nonlinear fastener are more effective to attenuate the vibration of rail to channel bed(floating plate),while steel spring floating plate and rubber floating plate are more effective to attenuate the vibration from track bed(floating plate)to tunnel wall.(2)The model of elastic short sleeper and pioneer fastener is compared with the measured results.The rationality of the model is verified and the influence of different static load on single wheel,different elastic modulus and combined vibration reduction is analyzed.The results show that the acceleration and vibration level of rail,track bed and tunnel wallwill increase with the increase of static load of single wheel,and the increase of elastic modulus of rubber sheath under the pillow will cause the increase of acceleration and vibration level of rail,track bed and tunnel wall.However,the increase of rubber elastic modulus on both sides of rail does not necessarily lead to acceleration and increase of vibration level.The damping effect of the combination of the pioneer fastener and the elastic short sleeper is not as good as that of the single damping measure(the pioneer fastener or the elastic short sleeper),and the increase of the rubber elastic modulus on both sides of the rail does not necessarily cause the acceleration and the increase of the vibration level.(3)The results of ordinary track bed model with or without new type H damping measures are compared,the results of the new type H damping measures are verified,and the parameters of different velocity,different modulus of elasticity and different damping loss factors are analyzed.The results show that the new H-type damping measures can attenuate the acceleration and vibration level of rail,track bed and tunnel wall,and the damping effect is 3.4 dB,and the increase of velocity will cause the acceleration and vibration level of rail,track bed and tunnel wall to increase.However,the increase of H-type vibration reduction measures will slow down the increase of rubber elastic modulus of vertical members when the horizontal elastic modulus of H-type damping measures is smaller,and the increase of rubber elastic modulus of vertical members will reduce the vibration.The increase of damping loss factor will cause the acceleration and vibration level of rail,track bed and tunnel wall to decrease,but the amplitude of decrease is very small.