Measurement of Roller Compactor Induced Triaxial Soil Stresses and Strains

The measurement of soil properties via roller compactor-integrated instrumentation has gained increased attention. Employing roller-based measurement of mechanistic soil properties for quality assurance or performance prediction has significant potential benefits. To advance the development and understanding of static and vibratory roller measurement systems, the geotechnical community must better understand soil behavior during roller loading. This paper describes the development and implementation of an experimental program to measure in-situ triaxial normal stresses and strains during static and vibratory roller passes. Field tests revealed complex triaxial stress-strain behavior with near plane-strain conditions beneath the center of the drum. The observed stress response matched well with behavior predicted by Hertzian elastic contact theory. The soil stiffness dependent drum/soil contact width plays a significant role in stress distribution and depth of influence of the roller. The influence of drum vibration and static roller weight are visible in stress and strain measured during vibratory operation. The curved drum significantly influences the induced stresses and strains. The results presented here reveal that rollers induce stresses and strains to depths approaching 2 m and that the stress state imparted by the roller is more complex than that used in resilient modulus testing.