Stochastic Solution to the Subgrade Resilient Modulus: Monte Carlo Approach

The AASHTOware pavement design procedure is based on a hierarchical approach where a greater number of input parameters are determined by laboratory testing when the magnitude, cost and importance of the project increase. The characterization of unbound materials is accomplished by the estimation of the resilient modulus based on either laboratory measurements (Level 1), correlations with other properties (Level 2), or values based on local experience (Level 3). The procedure makes use of deterministic solutions which are difficult to interpret due to the lack of information related to the compound variability associated with soil heterogeneity and environmental conditions. This document presents a general framework for a stochastic solution to estimate the equilibrium resilient modulus of unbound materials based on the Monte Carlo simulation using the Beta distribution. To illustrate the practicality of the stochastic approach, the document presents a comparison of the results when different hierarchical levels of analysis are used. The analysis presented is fundamental in any decision-making stage within the design and construction control of projects and can easily be adapted to other civil infrastructure analysis.