Application of Stochastic Finite-Element Method to Deflection Analysis of Pavement Structures

Abstract

The effect of random variations in layer properties of a pavement-subgrade system on surface deflections is investigated. This is done by using a stochastic finite-element framework based on the perturbation method. The Taylor's expansion scheme is used. The variations of the surface deflections are related to the variations of layer moduli via a coefficient matrix, thereby allowing an investigation of the sensitivity of measured deflections to the variation of pavement and subgrade moduli. The analyses confirm that surface deflections are not very sensitive to variations of modulus within the pavement structure. Using the Boussinesq-Odemark approximation, it is concluded that, for the sample problem analyzed, the effect of higher-order terms on variation estimates of displacement is negligible when the coefficient of variation of subgrade modulus is less than 15 percent. The effect of inertia on the coefficient of variation of displacement due to variations in layer moduli is also briefly addressed. It is demonstrated that the variation in displacement under the load is sensitive to both the loading frequency and the equivalent mass of the pavement-subgrade system, particularly in the vicinity of the natural frequency of the system.