Traffic load is one of the main factors that cause permanent deformation in the pavement, which is an important factor specifying road life and serviceability related to traffic safety. In addition to truck axle load level, deformation level in road pavement depends on superstructure materials, subgrade conditions, climate, groundwater conditions, number of load repetitions, and loading frequency. Loading frequency affects both the deformation level in pavement layers and the stress state. In this study, the effect of loading speed (loading frequency) was evaluated by carrying out a finite element analysis of certain flexible road pavement cross-sections under 400 kPa pressure. A triangular load pulse with 400 kPa was loaded on pavement cross-sections with different loading speeds. The analyzed cross-section of flexible road pavement consists of asphalt concrete layer, unbound base, and subbase layers. Subgrade material is the clay layer. For dynamic analyses of road pavement under the repetitive load of different loading speeds, 2D axial symmetric analyses were performed. The Hardening Soil Model with Small Strain Stiffness (HSsmall) soil model was used for modeling unbound granular layers and subgrade soil. Asphalt concrete was modeled with the Mohr-Coulomb material model. The tire contact area was assumed as a square area within 300 mm side length. Loading pulse durations were calculated for different loading speeds. The analyses show that the total vertical deformation for the analyzed section has a minimum value of 90 km/h loading Speed (6.94 Hz). As the loading speed increases or decreases, the total vertical deformation of the cross-section on either side of this point increases. The deformation graph has two local maximum points because of the resonance of the pavement system. These results are consistent with previous studies. Results show that controlling the loading speed will lengthen the road serviceability life by reducing the deformation.

Flexible Pavement; Traffic Load; Frequency; Loading Speed; Response of Flexible Pavement