Experimental Studies in Vibration-Insulating Properties of Blocks in Resilient Fastening for Metro Rail Track

Аннотация

The results of experimental studies in vibration-insulating characteristics of a resilient rail track of metro are given. The studies were carried out on fragments of a rail track made of reinforced-concrete slabs with the dimensions 1.5 x 3 x 0.2 m, with the rail grid fragments installed on them (in concrete), made of: 1 – vibration-insulating blocks, EBS system; 2 – concrete blocks with the resilient fastening system, 300 UTS Vossloh; 3 – timber sleepers (the basic option). The static stiffness values of vibration- insulating blocks system were as follows: 17.9 kN/mm, for ЕВS type blocks (the vibration-insulating pad and the resilient insulation layer), and 17.2 kN/mm, for 300 UTS Vossloh type blocks (vibration-insulating pad stiffness). Tests were carried out by installing a vibration exciter on the rail track, with the weight 75 kN, provided with two industrial vibrators: 1 – with the exciting force 20 kN and frequency 50 Hz; 2 – with the exciting force 24.2 kN and frequency 25 Hz. The values of maximum root-mean-square vibration acceleration readings taken in test points of the concrete seat were used to assess the degree of vibration insulation for rail track systems. The vibration acceleration levels were measured in 31.5 Hz and 63 Hz frequency ranges; for this purpose, Oktava 101- VM three-channel vibration meter was used. The software, R110, version 1.20, was used to process the signals from vibration sensors.

It was found that, from two types of concrete blocks, the highest vibration insulation for the rail track seat is provided when EBS type blocks are used. In the root-mean-square frequency range 31.5 Hz, the vertical vibration level reduction to 4.3 dB was reached; in the frequency range 63 Hz, from 3.0 to 10.6 dB. The vibration level reduction in horizontal directions was, respectively, from 2.7 dB to 13.8 dB and from 3.1 to 11.4 dB.

As compared with the rail track on timber sleepers, EBS type blocks provide reduction of vertical vibration in 31.5 Hz frequency range from 3.2 dB to 11.1 dB. As for the vibration level in the rail track seat with EBS type blocks in the horizontal direction (longitudinal and transverse) at frequency 63 Hz, it is higher by 2.5–7.7 dB, that can be explained by damping effect of timber sleepers due to their large size including presence of cracks.

Keywords: vibration-insulating reinforced-concrete blocks, metro rail track fragments, vibration insulation tests, vibration accelerations.

For citation: Shepelevich M., Kanaplitski A. Experimental Studies in Vibration-Insulating Properties of Blocks in Resilient Fastening for Metro Rail Track. In: Contemporary Issues of Concrete and Reinforced Concrete: Collected Research Papers. Minsk. Institute BelNIIS. Vol. 9. 2017. pp. 80–95. https://doi.org/10.23746/2017-9-6

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