Evaluation of long term performance of asphalt concrete track under train speeds and temperatures in service line

Abstract

Asphalt concrete (AC) tracks are known to reduce maintenance costs and efforts by improving bearing capacity, enhancing the stability and durability of track structures, and reducing vibration and noise. In addition, train operation can be started quickly after asphalt paving is completed, and the track can be quickly restored in the event of major deformation due to derailment, etc., and it is a recyclable material. But one of the most important environmental factors affecting the mechanical properties of asphalt mixtures is temperature, that is, temperature distribution and environmental conditions of asphalt concrete track have influence on the performance. Therefore, in order to verify the temperature effect on asphalt concrete tracks, the pressure acting on the upper surface of the subballast layer and the strain of the lower surface of the asphalt layer were measured during one year of train operation. In this study, the load distribution characteristics, plastic deformation and crack resistance according to temperature, and theoretical and analytical analyses based on domestic and international design standards were conducted for the structure of asphalt concrete track, specifically the asphalt concrete layer and subballast layer. AC tracks are affected by temperature as in previous literature, and show larger values compared to the values of Fixed point load tests, but the pressure of the subballast layer directly underneath the rail is 46.68 kPa to 54.81 kPa, which is within the allowable subballast pressure (133 kPa), and the asphalt layer strain rate also shows a low value of 17.19–21.58με. Through this research, it was confirmed that asphalt concrete track meets the design standards and possesses excellent load distribution characteristics, plasticity, and crack resistance. In addition, numerical simulations were conducted to analyze the influence of train speed, and the results showed that asphalt concrete tracks can ensure safety in terms of support even when a train runs at 350 km/h.