Vertical coupling dynamics model of heavy truck-pavement-subgrade

In order to investigate the dynamic interaction of heavy truck, pavement and subgrade induced by road roughness, a heavy truck-pavement-subgrade vertical coupling dynamics model was formulated. In this model, the heavy truck was modeled as a multi-degrees of freedom rigid body in uniform motion, which was connected by a series of springs and damping devices. The surface layer was modeled as a continuous thin plate with inner damping supported by discrete base block. The base layer was modeled as several discrete bodies supported by the viscoelastic subgrade. Then Wilson-θ method was used to solve the coupling dynamics model and to verify the reliability of the model. The results show that the dynamic effects of the moving heavy truck are remarkable. The tire force and dynamic displacement of pavement induced by 5-axial heavy truck are greater than other axis types, which display an linear increase with the increase of rear axis loads. The peaks of tire force and dynamic displacement of pavement increase with the increase of moving speed, but the average of dynamic displacement of pavement changes a little. When the grade of road roughness descends from grade A to grade D, tire force amplification increases more than one time, and the peak of pavement displacement increases by 72%. Subgrade stiffness show a little effect on tire force, but a great effect on dynamic displacement of pavement.