Improvement Thicknesses To Increase Subgrade Strength In Flexible Road Pavements

Abstract

The technique of placing a granular improvement material, a common procedure in Ecuador, allows an increase in the resistance of the subgrade soil, achieving greater support capacity. A theoretical procedure is presented in the article to determine these minimum thicknesses, obtained by modeling soil structures using the ALIZE software. The applied procedure is based on the method included in the Instruction for the Design of Road Surfaces of the Andalusian Road Network (ICAFIR), with some modifications to adapt it to the AASTHO 93 design standard. The load plate test is modeled by applying a load of 0.5MPa on a multilayer model, formed by the natural soil and the improvement material, calculating the surface deflection and the elastic modulus on the surface. Required categories have been established for the subgrade based on the design CBR, low (5%), medium (10%) and high (15%), according to the light, medium and heavy design traffic, respectively. Depending on the type of traffic and the quality of the natural subgrade, the minimum improvement thicknesses that must be used to guarantee the modules required in the foundation of a flexible pavement are provided.