Study and calculation of soil compaction during operation and after stopping of a wheeled tractor

Based on the results of theoretical studies and field tests, the mathematical modeling is performed for the processes of soil deformation and compaction during operation and after stopping of a wheeled tractor. The purpose of the study is to develop the earlier proposed calculating method of stress-strain state and soil compaction indicators during the operation of tractor and under soil creep after its stopping. The novelty of the paper consists in the fact that calculations are performed taking into account the viscoelastic properties of soil and changes of its density depending on time and on depth of deformable layer. The impact of soil load taking into account the viscoelastic properties of soil is described by a differential equation of first order connecting the compressive stresses, the rate of their change and relative deformations of compression. Viscoelastic properties of sward-podzolic light loamy soil revealed in field tests are considered. Soil density is variable by depth of its top deformable layer. Following the results of statistical processing of experimental data, the dependence of soil density on its depth before the impact of external loads is admitted as quadratic one. Computer experiments are performed; they revealed the indicators allowing to estimate quantitatively the changes of soil deformations, stresses and density during the operation of tractor and under soil creep after its stopping. Correlation dependencies of these indicators on the time, soil density and moisture, and on the speed of initial soil deformation are obtained. The proposed calculation method allows to find the above mentioned indicators for different depths of deformable soil layer, and also the stabilization time of soil deformation.

rheology, deformation, compressive stress, soil compaction, viscoelastic properties of soil, creep, mathematical modeling