Mechanical response analysis of CRC+AC composite pavement asphalt layer during thermo-mechanical coupling

Based on heat transfer, mechanics and material sciences, a thermal-mechanical coupling model of CRC+ AC composite pavement structure with joints was established using ABAQUS finite element analysis software, and the reliability of the coupling model was verified by actual engineering deflection and temperature. The established thermo-mechanical coupling model was used to study the influence of asphalt layer thickness, axle load size, driving speed and continuous reinforced concrete layer micro-crack width on the mechanical response of CRC+AC composite pavement structure asphalt surface layer, and orthogonal experiments were designed to study the sensitivity of the asphalt surface layer's mechanical response to various influencing factors, and analyze the stress evolution characteristics and cracking inducements on the surface and bottom of the asphalt layer. The results show that the various influencing factors have little effect on the transverse and longitudinal stresses on the asphalt layer surface, and the asphalt layer thickness and CRC layer microcracks have little effect on the asphalt layer surface shear stress. With the increase of vehicle axle load from 100 kN to 160 kN, the shear stress increases by about 24.10% on the asphalt layer surface. With the increase of driving speed from 60 km/h to 120 km/h, the asphalt layer surface shear stress decreases by 12.00% on the asphalt layer surface. The asphalt layer bottom transverse tensile stress decreases by 88.90%, the bottom longitudinal tensile stress reduces by 88.70%, and the bottom shear stress reduces by 56.70% with the increase of asphalt layer thickness from 6 cm to 14 cm. The transverse tensile stress of the asphalt layer reduces by 56.6%, the longitudinal tensile stress reduces by 62.10%, and the shear stress increases by 85.50% with the increase of vehicle axle load from 100 kN to 160 kN. The asphalt layer bottom transverse tensile stress increases by 13.80%, the longitudinal tensile stress increases by 18.50%, and the shear stress decreases by 11.50% with the increase of driving speed from 60 km/h to 120 km/h. The asphalt layer bottom transverse tensile stress increases by 40.20%, the longitudinal tensile stress increases by 60.10%, and the shear stress increases by 2.56% with the increase of the crack width of CRC layer from 0.5 mm to 1.3 mm. The influencing factors of the tensile and shear stress on the bottom of the asphalt layer from large to small are asphalt layer thickness, vehicle axle load, CRC micro-crack width and driving speed. The main influencing factors of asphalt layer surface tensile and shear stress are asphalt layer thickness and vehicle axle load. The asphalt layer thickness should be reasonably designed in engineering practice, and the axle load of the vehicle to control the early cracking of the asphalt layer should be considered. © 2023 Central South University of Technology. All rights reserved.