TY - JOUR

T1 - The mechanical behavior of structured and homogenized soil under repeated loading

AU - Peth, Stephan

AU - Horn, Rainer

PY - 2006/4

Y1 - 2006/4

N2 - Soil deformation is increasingly important in crop production since nowadays weights of agricultural machines exceed the bearing capacity of most soils. Often this is counteracted by distributing the weight over more axles leading to an increase in wheeling frequency. Machine passages during one year can, depending on the crop and equipment used, range between two and five times for the majority of the field and up to twenty times and more for a wheeling track. These add up to hundreds of loading events for a crop-rotation period. In this study, we investigated the effect of multiple loading with the same load in a cyclic-compression test on soil-pore-volume change. The tests were conducted on homogenized soil samples with varying texture and undisturbed soil samples from a field experimental site comparing conventional and conservation-tillage systems. Of particular interest was the question whether there is significant plastic soil deformation for soil stresses that remained sufficiently below the precompression stress, which is commonly neglected. Our results show that especially for cohesive soils, the assumption of fully elasticity in the recompression range may not be justified since those soils show distinct cyclic-creep behavior. We found that deformation under cyclic loading follows a logarithmic law. We used the slope of the logarithmic fit of void-ratio changes vs. loading cycles as a parameter to characterize the sensitivity of soils to cyclic compression. The results suggest that for characterizing the mechanical stability of soils that show cyclic creep, we have (with respect to long-term deformation effects) to consider both precompression stress and cyclic compressibility.

AB - Soil deformation is increasingly important in crop production since nowadays weights of agricultural machines exceed the bearing capacity of most soils. Often this is counteracted by distributing the weight over more axles leading to an increase in wheeling frequency. Machine passages during one year can, depending on the crop and equipment used, range between two and five times for the majority of the field and up to twenty times and more for a wheeling track. These add up to hundreds of loading events for a crop-rotation period. In this study, we investigated the effect of multiple loading with the same load in a cyclic-compression test on soil-pore-volume change. The tests were conducted on homogenized soil samples with varying texture and undisturbed soil samples from a field experimental site comparing conventional and conservation-tillage systems. Of particular interest was the question whether there is significant plastic soil deformation for soil stresses that remained sufficiently below the precompression stress, which is commonly neglected. Our results show that especially for cohesive soils, the assumption of fully elasticity in the recompression range may not be justified since those soils show distinct cyclic-creep behavior. We found that deformation under cyclic loading follows a logarithmic law. We used the slope of the logarithmic fit of void-ratio changes vs. loading cycles as a parameter to characterize the sensitivity of soils to cyclic compression. The results suggest that for characterizing the mechanical stability of soils that show cyclic creep, we have (with respect to long-term deformation effects) to consider both precompression stress and cyclic compressibility.

KW - Air capacity

KW - Cyclic compressibility

KW - Mechanical stability

KW - Precompression stress

KW - Soil deformation

UR - http://www.scopus.com/inward/record.url?scp=33745776679&partnerID=8YFLogxK

U2 - 10.1002/jpln.200521942

DO - 10.1002/jpln.200521942

M3 - Article

AN - SCOPUS:33745776679

VL - 169

SP - 401

EP - 410

JO - Journal of Plant Nutrition and Soil Science

JF - Journal of Plant Nutrition and Soil Science

SN - 1436-8730

IS - 3

ER -