Design Method for Geogrid-Reinforced Unpaved Roads. I. Development of Design Method

TLDR

The paper develops a theoretically based design method for determining the base course thickness of geogrid‑reinforced unpaved roads, incorporating stress distribution, material strength, interlock, geosynthetic stiffness, and traffic conditions. The method calculates the required base course thickness with a single unique equation, simplifying previous multi‑equation approaches, and is applicable to geogrid‑, geotextile‑reinforced, or unreinforced unpaved roads. Calibration of the method using field wheel‑load and laboratory cyclic plate‑loading data for both unreinforced and reinforced base courses is detailed in a companion paper.

Abstract

A theoretically based design method for the thickness of the base course of unpaved roads is developed in this paper, which considers distribution of stress, strength of base course material, interlock between geosynthetic and base course material, and geosynthetic stiffness in addition to the conditions considered in earlier methods: traffic volume, wheel loads, tire pressure, subgrade strength, rut depth, and influence of the presence of a reinforcing geosynthetic (geotextile or geogrid) on the failure mode of the unpaved road or area. In this method, the required base course thickness for a reinforced unpaved road is calculated using a unique equation, whereas more than one equation was needed with earlier methods. This design method was developed for geogrid-reinforced unpaved roads. However, it can be used for geotextile-reinforced unpaved roads and for unreinforced roads with appropriate values of relevant parameters. The calibration of this design method using data from field wheel load tests and laboratory cyclic plate loading tests on unreinforced and reinforced base courses is presented in the companion paper by the authors.