Due to the growing demand for timber, forest soils are increasingly exposed to mechanical disturbances, caused by forestry equipment. Even though using skidding machines to transport wood is detrimental to the physical state of the soil, this method remains the most common. Hence, there is a need to model the impact of skidding systems on the upper (fertile) layer of the soil. This study aims to develop such a model using the D'Alembert principle, the method of Laplace transforms, and a modified Kelvin-Voigt model. The work shows that subdividing the tractor-bundle-soil system makes it possible to consider the dynamic effect of the vibrating tractor on the soil and soil's ability to undergo deformation separately. In addition, the study developed individual models for the first subsystem that determine vibration effects on soil caused by an unloaded tractor and two loaded skidding systems using different methods of semi-suspended skidding. The present findings can be used to predict the degree of dynamic soil compaction without conducting direct on-site experiments and thus minimize the negative impact of forestry operations on the local ecosystem. The current data also allow simplifying design models for complex forwarders.
Keywords: compaction; deformation; modeling; oscillation; skidding; system.