The resilient moduli of subgrade soils in The East Tennessee Area

The resilient deformation of a flexible pavement system due to the application of traffic wheel loads on the road surface is a good indicator of pavement performance. In many cases, more than two thirds of the measured deflection has been attributed to the subgrade soil underlying the pavement. The resilient modulus identifies a soil by its behavior under repeated loading conditions.

A program was implemented to determine the resilient moduli of soils in East Tennessee. Laboratory equipment was fabricated and a testing procedure was adopted. A computerized data acquisition system was set-up and computer programs were written to reduce the data.

Fine-grained soil samples were collected from three sites in the East Tennessee area. The soil index properties of each sample were determined from standard laboratory tests. Repeated load tests were conducted on the compacted samples over a range of deviator stresses. Variations in the testing stress level and material properties such as water content and dry density were found to significantly affect the resilient modulus.

A second order polynomial equation, in terms of deviator stress and the degree of saturation, was utilized to predict resilient modulus values.