Soil Deformation as a Dynamic Process and Its Relation to Structure and Soil Water Pressure.

Measurement and modeling of stress-strain relationships for various loading conditions and field traffic intensities are useful tools to assess and predict soil deformation and estimate related changes in soil functions such as aeration and hydraulic conductivity. Pre-compression stress for example is a well known parameter for characterizing the stability of soils against volumetric deformation. Its determination is based on static soil compression tests. Especially in agricultural land use, however, soil deformation is caused by dynamic rather than static loading processes where in situ stress-strain paths diverge from the conditions applied during standard static soil testing. This also affects hydraulic stress developments during wheeling and a potential feedback on the mechanical stress attenuation and subsequent deformation processes.

To investigate the coupling between hydraulic and mechanical stresses under dynamic loading conditions we measured soil deformation and associated pore water pressure changes in a confined compression test under various stress paths. The potential of dynamic soil testing for predicting and modeling soil compaction will be demonstrated and the role of pore water pressure changes for the deformation process will be discussed.