Dynamic Response of Asphalt Pavement Under Multi-wheel Dynamic Load

Abstract

Though the stress of each structural layer of asphalt pavement under vehicle loads is complex, the current design specification of highway asphalt pavement has failed to cover vehicles' vibratory characteristics and rubber tires' nonlinearity. Therefore, to study the dynamic response of asphalt pavement under multi-wheel dynamic loads, based on the theories of vehicle dynamics, hyperelasticity of rubber material, and viscoelasticity of asphalt pavement, a three-dimensional finite element model of the vehicle-rubber tires-asphalt pavement was built. Its reliability was verified by comparisons with actual vehicle-road field measurements to contrast and analyze the dynamic response of pavement's structural layers under no road roughness and class B road roughness. Results show that by being compared with the measurement results of actual vehicle-roads, the error between the maximum longitudinal shear strain at the bottom of the asphalt layer and the measured value is 5.889%, which shows that the vehicle-road dynamic model is reliable and reasonable. Under the excitation of road roughness class B, the grounding normal force of the left single wheel of the rear axle is between 0 - 86.526 kN, the normal acceleration of the vehicle is between -0.451 - 0.372 m•s-2, and the elastic force of the rear axle left suspension is between 60.376 - 68.42 kN. Compared with no road roughness, the maximum grounding normal force of the left single wheel on the rear axle, maximum normal acceleration of the vehicle, and maximum elastic force of the rear axle left suspension increase by 113%, 402.7%, and 7.4%, respectively. Compared with no road roughness, the longitudinal maximum compressive stresses of the upper, middle, and lower layers increase by 18.91%, 12.4%, and 21.1%, respectively, and the longitudinal maximum tensile stresses increase by 3.94%, 6.25%, and 33.3%, respectively. The transverse maximum compressive stresses increase by 10.43%, 8.47%, and 9.19%, respectively, and the transverse maximum tensile stresses increase by 12.19%, 13.08%, and 33.33%, respectively. The value of compressive stress is much greater than that of tensile stress. The vertical maximum compressive stresses increase respectively by 19.1%, 19.35%, and 20.07%; the vertical maximum tensile stresses increase respectively by 26.93%, 7.38%, and 6.2%; and the compressive stress of the front wheels is greater than that of the middle and rear wheels. The above data show that road roughness has a great influence on the response of the structural layer and that the vibratory characteristic of vehicles and the nonlinear contact between rubber tires and road surfaces should not be ignored.