Comparative Evaluation of Subgrade Resilient Modulus from Non-Destructive, In-Situ, and Laboratory Methods; Final rept

摘要

Field and laboratory testing programs were conducted to develop models that predict the resilient modulus of subgrade soils from the test results of DCP, CIMCPT, FWD, Dynaflect, and soil properties. The field testing program included DCP, CIMCPT, FWD, and Dynaflect testing, whereas the laboratory program included repeated load triaxial resilient modulus tests and physical properties and compaction tests. Nine overlay rehabilitation pavement projects in Louisiana were selected. A total of four soil types (A-4, A-6, A-7-5, and A-7-6) were considered at different moisture-dry unit weight levels. The results of the laboratory and field testing programs were analyzed and critically evaluated. A comprehensive statistical analysis was conducted on the collected data. The results showed a good agreement between the predicted and measured resilient modulus from the various field test methods considered. The DCP and CIMCPT models were enhanced when the soil moisture content and dry unit weight were incorporated. The results also showed that, among all backcalculated FWD moduli, those backcalculated using ELMOD 5.1.69 software had the best correlation with the measured Mr. Finally, the Mr values estimated using the approach currently adopted by the LADOTD were found to correlate poorly with the measured M(sub r) values.