Measuring and predicting Stress Distribution under Tractive Devices in Undisturbed Soils

The objective of this study was to compare predicted stresses with measured stresses within the soil profile underneath a tractor rear tyre as affected by soil type, dynamic load, and contact pressure. The major principal stress, octahedral normal stress, and octahedral shearing stress were compared. A three-dimensional non-linear finite element model was used to predict soil profile stresses while stress state transducers were used to measure soil stresses beneath a moving tyre in the field. Principal stresses, octahedral normal stresses, and octahedral shearing stresses were calculated from the measured stresses. Predicted values of soil stress obtained from the finite element model were compared against measured values obtained from field experiments. Generally, the results from the finite element model were found to be compatible with the experimental results. The study of compaction on two soils indicated that, at the same dynamic load, compaction of clay soils was far more severe than that of coarsely textured soils.