Investigation into the Evaluation Method for Vibration Damping Effect of Track Systems

The railway has taken measures for the track to decrease vibration,and actually obtained effect of the vibration damping should be evaluated.A method to evaluate the vibration damping effect of track systems is established on the basis of comprehensive analysis of evaluation status and existing problems.In order to increase the track elasticity on various levels of rail fastenings,sleeper or bed etc.,the elastic elements were inserted extra in the track system.Under the same or comparable conditions,the vertical accelerations at the measurement points of trackside were used by a comparison of both track systems without/with the vibration reducing measures.The mean effective value of the vibration damping effect is calculated by the differences between the root-mean-square values which were on the basis of vibratory acceleration levels at each centre frequency in one-third-octave,and moreover,the maximal/minimal difference between levels at some centre frequency in one-third-octaves can be used as assistant evaluated index.The evaluating method was applied to the frequency range between 4and 200Hz to estimate the vibration damping effect for 3types of different track structures with the vibration damping fastener,block sleepers with rubber-plastic boots and floating slab track etc.The results show as follows.By vibration damping fastener,a mean effective value of 5.2dB is obtained and the vibration damping has an obvious effect from the frequency range of 50Hz;by floating slab track,a mean effective value of 13.5Hz is able to fulfill the design requirement that the damping performance value is greater than 10dB;the block sleepers with rubber-plastic boots have a damping effect only in the value of 3.8dB,the design goal is not attained resulted from unsupported sleepers.The evaluation method can be used not only for comparing the damping effect by various track structures,every line sections and possible operating conditions as well as the same track structure in different lines,but also for analyzing the damping performance of the track systems.