Estimating the coefficient of at-rest earth pressure in granular pavement layers

Compaction of pavement layers composed of unbound granular materials increases the at-rest earth pressure coefficients. These coefficients influence the stress-state in the material and are therefore important for modeling pavement behavior; they may also serve as indicators, alongside densities, of compaction quality. Given the inability of geotechnical tools to directly measure the coefficient of at-rest earth pressure in granular pavement layers the paper offers an estimation approach that is computational in nature. The scheme is based on solving a multi-objective inverse problem and requires a pavement instrumented with implanted sensors, preferably monitoring a wide variety of response types. It also requires laboratory resilient modulus information of granular specimens compacted to in situ densities. In order to demonstrate the computations, a simplified version of the method is applied to an airport pavement system tested in an accelerated loading facility. Post-construction at-rest earth pressure coefficients of the base and subbase layers are quantified and evaluated for reasonableness. It is concluded that the approach, even in its simplified form, is capable of producing realistic estimates.