Analysis of granular bases using discrete deformable blocks

A method of analysis using fully deformable blocks is proposed for modeling unbound granular layers used in flexible pavements. An assemblage of discrete blocks of aggregates is employed to approximate the load transfer mechanisms of the real particulate nature of granular materials. The unbound aggregate bases were modeled as particulate media composed of blocks of aggregates, which are able to transfer both shear and normal compressive loads through the interfaces. Using a finite-element approach, the discrete blocks are modeled as single quadrilateral elements connected only by surrounding interface elements at each block interface. Realistic granular layer particle characteristics including translation, sliding, and even separation are permitted for each block. An iterative procedure for equilibrium is employed in the model, and the constitutive relations used in the analysis are described for determining the behavior modes of the interface elements. The granular base discrete block representation is then used in a conventional flexible pavement section having other layers modeled as continua. Important findings are presented related to the shear reistance of the granular bases.