Rut Formation, Soil Strength Changes and Energy Demand Under Repeated Pneumatic Wheel Passes in a Soil Channel

The study analyzes the rut formation process, changes in the physical and mechanical characteristics of the soil, and the energy demand associated with movement of the driven pneumatic wheel during repeated passes on the same track in a laboratory soil channel stand. The tests were performed on a prepared silty loam at an average moisture of 30.64%. Three vertical wheel loads were investigated: 4.84 kN, 6.94 kN, and 8.75 kN without a brush mat, as well as a vertical load of 8.75 kN with a brush mat. After each pass, the average rut depth, its increment, and the average dynamic penetration resistance were determined. For tests without a brush mat, soil shear resistance, power, work performed per pass, and work per 1 m of path were additionally determined. It was established that the rut depth increased non-linearly. The greatest increment was formed during the initial passes, after which the deepening rate decreased. In the tests without a brush mat, the final rut depth showed a trend of increasing with load: 8.1 cm for 4.84 kN, 9.2 cm for 6.94 kN, and 9.9 cm for 8.75 kN. The brush mat was associated with lower accumulation intensity of the rut depth and lower average dynamic penetration resistance in the soil. The change in rut depth is described with sufficient accuracy by a regression model with R2 = 0.9512–0.9761 and RMSE = 0.194–0.344 cm. Energy indicators showed that the first pass was the most energetically intense, and the calculated work characterizes the total work of the wheel movement, not just the work of rut formation. The results confirm nonlinear rut accumulation with the highest increment during initial passes, and the highest energy demand during the first pass. The fitted model provides an engineering tool for estimating permissible pass numbers, while the integrated geometric–mechanical–energy approach offers a more comprehensive basis for planning forestry traffic than conventional bare-soil compaction tests.