IMPACT ASSESSMENT OF ASPHALT CONCRETE IN GEOGRID-REINFORCED-PILE-SUPPORTED EMBANKMENT DURING HIGH-SPEED TRAIN TRAFFIC

Railroad structural behaviour is a significant factor for safety and comfort during high-speed train operation. Intending to improve railway performance, increase its bearing capacity, and reduce vibrations induced by train passage, asphalt concrete has become a material to be integrated into railway construction. Despite several studies evaluating asphalt concrete effect on the railway mechanical behaviour, its impact assessment remains poorly understood. This study investigates the impact of asphalt concrete material in the geogrid-reinforced-pile-supported embankment structure subjected to high-speed train moving. A 3D nonlinear finite element model was developed to simulate Harbin (Dalian (China) instrumented railroad test section accurately. The high-speed train moving load was modelled as a transitory dynamic load via a user-defined subroutine 3D load in which the track irregularity is incorporated. The established model was effectively validated by the vibration acceleration and stress measured in the field test section. The asphalt concrete viscoelasticity behaviour was incorporated into the 3D geogrid-reinforced-pile-supported embankment finite element model through the Prony series to characterise its mechanical response better. The impact of asphalt concrete material in maintaining a low and constant structural vibration, regardless of train weight level, moving speed variations, and weather conditions were investigated, analysed and discussed.