• Lamandé, Mathieu
• Arvidsson, J.
• Schjønning, Per
• Weisskopf, P.
• Stettler, M.
• Keller, T.

Abstract

Soil compaction negatively influences many important soil functions, including crop growth. Compaction occurs when the applied stress, [sigma], overcomes the soil strength. Soil strength in relation to compaction is typically expressed by the soil precompression stress, [sigma]pc. Deformation is assumed to be elastic and reversible as long as [sigma] <= [sigma]pc. This work examined soil stress-strain behavior as measured in situ during wheeling experiments and related it to the stress-strain behavior and [sigma]pc measured on soil cores in uniaxial compression tests in the laboratory. The data analyzed were from a large number of wheeling experiments carried out in Sweden and Denmark on soils with a wide range of texture. Contradicting the concept of precompression stress, we observed residual strain, [Latin Small Letter Open E]res, at [sigma] <= [sigma]pc. These observations were supported by stress-strain data measured in uniaxial compression tests, which likewise showed [Latin Small Letter Open E]res > 0 at [sigma] <= [sigma]pc. Residual strain was observed in the field when [sigma] exceeded approximately 40 kPa, and when the ratio [sigma]/[sigma]pc exceeded roughly 0.1, although [Latin Small Letter Open E]res was very small at [sigma]/[sigma]pc < 0.5. These values were similar to those obtained on confined uniaxial compression curves. On the basis of our findings, we question the use of [sigma]pc as a measure of soil strength and call for a reevaluation of the precompression stress concept.

Topics

• impedance spectroscopy
• experiment
• strength
• stress-strain behavior
• compression test
• texture