Seong-Wan Park

Analysis of Stress-Dependent Behavior in Conventional Asphalt Pavements

Most low-volume roads are primarily thin flexible pavements with unbound base and subgrades whose materials are nonlinear and stress-dependent even under low traffic stresses. A need therefore exists for predicting more realistic pavement response based on proper constitutive models and the computational method. In this study, the non-linear stress-dependent finite element program (FERUT) for pavement analysis was developed. Stress-dependent models for the resilient modulus and Possions Ratio of the unbound pavement materials were incorporated into the finite element model to predict the resilient behavior within the pavement layers under specified wheel loads. The results from this study show that the developed finite element model with the stress-dependency concept is suitable for taking into account for the effects of the non-linearity and stress-dependency of the unbound pavement layers in a pavement.

DISTINCT ELEMENT METHOD SIMULATION ON DEFORMATION MODE AND STRESS STATE FOR SPECIMEN SHAPE IN DIRECT SHEAR TEST

In order to examine the deformation mode and the stress state according to the specimen shape in the direct shear test (DST), a series of the three-dimensional DEM (distinct element method) simulations of the DST for sandy soils were carried out with the circular and the rectangular specimens. From the obtained results, the deformation mode of the rectangular specimen was under the plane strain condition, while the deformation mode of the circular specimen could not be explained as a plane strain condition. In addition, the principal stress states around the potential shear plane were analyzed and discussed by means of the analysis of the soil particle level.

A simplified mechanistic approach to establish load-limit on low-volume flexible pavements

A simplified mechanistic approach is presented for predicting load limits on low-volume flexible pavements. A non-linear elasto-plastic finite element program was developed to evaluate the structural adequacy of pavements based on a bearing capacity approach using the Mohr-Coulomb failure criterion. To consider the resilient behaviors, the stress-dependent model was also incorporated into the program. The varying stress-dependent modulus and Poissons ratio were predicted for considering the non-linear behaviors of unbound aggregate bases. A parametric study was also conducted to identify the significant resilient and plastic factors in a proposed methodology.