EFFECT OF WHEELING ON STRESS-DISTRIBUTION AND CHANGES IN THE MACROSTRUCTURE AND MICROSTRUCTURE OF A CAMBIC PHAEOZEM DERIVED FROM LOESS

The determination of stress induced changes in the poresystem due to repeated wheeling of a cambic phaeozem derived from loess as well as in the aggregate size distribution, arrangement, and stage are reported. It could be shown, that repeated wheeling always results in a further stress distribution to deeper depths and that the vertical stresses dominate with repeated wheeling. Furthermore the octahedral shear stresses and mean normal stresses exceed the maximum strength defined by the Mohr Coulomb failure line and define a further soil deformation. The process of aggregate deterioration can be verified by radiographs from which not only the changes in bulk density on a mesoscale can be derived but from which also the crack patterns can be defined for the different stages of structure deterioration. Under the well known assumption that pore water pressure is increased due to wheeling, soil compaction and consecutive soil homogenisation by kneading can be differentiated. The consequences for ecological parameters will be discussed.