Resilient Modulus Models for Compacted Cohesive Soils

Three-parameter models have been used to represent the effects of confining and shear stresses on the value of resilient modulus. A new generation of such models allows better characterization of the variation of resilient modulus at low deviator stress. These models can be extended to incorporate the effects of soil type, soil structure, and the soil physical state (combination of molding water content and dry unit weight) by relating the three parameters to explanatory variables consisting of common soil parameters. A simple methodology was applied to the results of 78 resilient modulus tests on low- and high-plasticity silts from the island of Oahu, Hawaii, to optimize the choice of explanatory variables. Then, the nonlinear ordinary least-squares method was used to estimate the model parameters. The results indicate that the new generation models not only provide a better fit than the older models, but they also provide a reasonable fit to the data that can capture the effects of stress state, soil type, soil structure, and the soil physical state quite effectively.