Analysis of the Influence of Fatigue Strength of Prototype Under Ballast Mats (UBMs) on the Effectiveness of Protection against Vibration Caused by Railway Traffic

Abstract

The present paper focuses on laboratory tests of fatigue strength of prototype under ballast mats (UBMs), carried out according to the procedure described in the new European standard EN 17282, which was released in October 2020. The mineral wool-based mat revealed significant differences in the values of static and dynamic characteristics, measured before and after the fatigue tests. The elastomeric mats based on recycled materials (SBR granulate and fibers) turned out to have had sufficient durability and effectiveness of protection against vibration caused by railway traffic. The values of static and dynamic bedding moduli, determined before and after the fatigue tests, were used to develop a viscoelastic rheological model of the vibration isolator with the use of fractional derivatives. Using this original model of the ballasted track system with four degrees of freedom, a significant influence of cyclic loading on the level of vibration suppression (insertion loss factor) was demonstrated. The analytical model confirmed that the mats with variations of bedding moduli exceeding 10% should not be used as resilient elements.

Under ballast mat – A review of recent developments, limitations, and future prospects

“…Although the elastomeric mats based on recycled materials (SBR granulate and fibers) turned out to have sufficient durability and effectiveness of protection against vibration caused by railway traffic, rubber-based UBMs have shown adequate fatigue strength in comparison to mineral wool ones. 65 Moreover, no visible damage, material chipping, perforations, or cracking was seen after fatigue tests on a rubber-based sample in Kraśkiewicz, Zbiciak. 65 In contrast to rubber-based mats, the mineral wool ones do not exhibit sufficient fatigue strength due to the fact that they reveal a significant variation in static and dynamic bedding modulus before and after the test.…”

“…65 Moreover, no visible damage, material chipping, perforations, or cracking was seen after fatigue tests on a rubber-based sample in Kraśkiewicz, Zbiciak. 65 In contrast to rubber-based mats, the mineral wool ones do not exhibit sufficient fatigue strength due to the fact that they reveal a significant variation in static and dynamic bedding modulus before and after the test. It can be identified from a research that exceeding the limit value of 10% of static and dynamic modulus after a laboratory test shows the unsuitability of the mineral wool mat.…”

“…It can be identified from a research that exceeding the limit value of 10% of static and dynamic modulus after a laboratory test shows the unsuitability of the mineral wool mat. 65 What is more, Sheng, Zheng, 26 found that rubber-based mats in ballastless tracks have a high energy absorbing capacity, and after 3,000,000 repeated loads, which is 1.5 times of a train axle load, the equivalent static stiffness only changes by 2%, indicating that the impact of the fatigue loads on the rubber UBM is not significant. 26 Environmental conditions.…”

“…The durability of UBMs is crucial due to the fact that in a ballasted or ballastless track structure, a replacement of UBMs will cause a major repair of the track structure (removal and reconstruction of all the structural elements). 65 UBMs have shown good efficiency in railway tracks; therefore, it is essential to investigate to see if aging affects the characteristics of the UBM. It was shown that ballast mats (Sylomer ® ) applied in the railway tunnel in Germany performed well with no serious changes in the dynamic loaddeflection properties after 18 years of service under extremely demanding load conditions.…”

Study on Possible Application of Rubber Granulate from the Recycled Tires as an Elastic Cover of Prototype Rail Dampers, with a Focus on Their Operational Durability

“…The contact with sharp edged ballast grains was simulated during the test by the geometric ballast plate (GBP) imposing dynamic pressure with a frequency of 5 Hz. Such plates are used in the tests of various elastic elements of track structures, for example under sleeper pads (USP) [26,27] which are tested according to EN 16730 [39] or under ballast mats (UBM) [28] which are tested according to EN 17282 [40].…”