Models to estimate subgrade resilient modulus for pavement design

摘要

Subgrade soil characterization, in terms of resilient modulus, is crucial for both flexible and rigid pavement design. Resilient moduli measured through repeated triaxial load tests on cylindrical disturbed/undisturbed samples are frequently used for characterizing subgrade soil. Because of the complexities encountered with the test, in-situ and other laboratory tests would be desirable if a reliable correlation can be established. In this paper, data from two-field test programs was used in developing correlation equations to predict resilient modulus of fine- and coarse-grained soils. Undisturbed samples are extracted from 12 in-service Mississippi subgrades, using a Shelby tube, and tested in a repeated triaxial machine for M_R employing AASHTO TP46-94 protocol. The results suggest two comprehensive models-one for fine-grained and another for coarse-grained soil-in correlating laboratory M_R to stress state. Model parameters are then correlated with soil index properties allowing the models to capture the effect of stress state, soil type and soil properties. For model verification, an independent set of data from nine different Mississippi subgrades is used, observing good comparison between actual and predicted moduli.