Resilient Modulus of Freeze-Thaw Affected Granular Soils for Pavement Design and Evaluation. Part 4. Field Validation Tests at Albany County Airport

摘要

Stress-deformation data for unbound base, subbase, and silty sand subgrade soils in two airfield pavements were obtained from in situ tests and laboratory tests. Surface deflections were measured in the in situ tests, with a falling-weight deflectometer, when the soils were frozen, thawed, and at various stages of recovery from thaw weakening. The measured deflections were used to judge the validity of procedures developed for laboratory triaxial tests to determine nonlinear resilient moduli of specimens in the frozen, thawed and recovering states. The validity of the nonlinear resilient moduli, expressed as functions of externally applied stress and moisture tension, was confirmed by using the expressions to calculate surface deflections that were found to compare well with deflections measured in the in situ tests. The tests on specimens at various stages of recovery are especially significant because they show a strong dependence of the resilient modulus on moisture tension, leading to the conclusion that predictions or in situ measurements of moisture tension can be used to evaluate expected seasonal variation in the resilient modulus of granular soils.