Modeling tire-soil compression resistance on artificial soil using the scaling law of pressure-soil sinkage relationship

Authors: JJAGWE, PIUS - Iowa State University; TEKESTE, MEHARI - Iowa State University; ALKHALIFA, NISREEN - Iowa State University; Way, Thomas - Tom

Submitted to: Terramechanics Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/12/2023
Publication Date: 4/13/2023
Citation: Jjagwe, P., Tekeste, M., Alkhalifa, N., Way, T.R. 2023. Modeling tire-soil compression resistance on artificial soil using the scaling law of pressure-soil sinkage relationship. Journal of Terramechanics. 108:7-19. https://doi.org/10.1016/j.jterra.2023.02.002.
DOI: https://doi.org/10.1016/j.jterra.2023.02.002

Interpretive Summary: Traction and soil compaction from vehicle tires and tracks running on soil are strongly influenced by dimensions and other aspects of the tire and track footprints. Optimal traction developed by tires and tracks is important for efficient tractive performance. Soil compaction from tires and tracks is often detrimental to crop production. An experiment was conducted to investigate effects of three scaled plates of various sizes and shapes and two soil bulk density conditions, on relationships between the pressure applied by a horizontal flat plate pressing downward on a soil surface and the sinkage of the plate into the soil. The soil, a sandy soil, was "artificial," meaning mineral oil was used as its moisture. The plate contact area was representative of a light truck tire footprint area. This study shows that using scaled-down plate contact areas, we successfully estimated parameters from traditional equations which relate plate contact pressure to sinkage.

Technical Abstract: Semi-empirical traction models use soil parameters estimated from the ASABE soil cone penetrometer and flat plate soil sinkage data. However, limited studies apply the scaling law of the soil measurement tool to a full-scale tire-to-soil system for various initial soil conditions. This study investigated the effects of three scaled plates (size and shape) and two soil bulk density conditions on pressure-sinkage relationships in artificial soil. A rectangular estimated tire-soil shape and a contact area of 484 cm^2 were measured from vertical loading of an LT235/75R15 tire (179 kPa inflation pressure and 8 kN vertical load) in a soil bin test on an artificial soil. Pressure-sinkage data were collected on an artificial soil column at 1.21 Mg/m^3 soil bulk density (66% of Proctor density) and 1.41 Mg/m^3 soil bulk density (75% of Proctor density) initial conditions using circular, rectangular, and square plates, each at three scaled areas (' = 0.5, ' = 0.25, and ' = 0.125, where ' =1 is the tire-soil estimated footprint area from the single tire soil bin test). A scaling law with a strong correlation was established between the geometric scale and the energy expended in compressing the soil. The plate pressure data for ' = 0.125 exhibited a relatively linear increase in pressure as depth increased for loose soil, similar to the soil cone penetrometer data. The pressure-sinkage data for '= 0.5 exhibited a trend similar to existing models, but coefficients differed for the two initial soil bulk densities. The study demonstrates applying a scaling law to simulate a tire-soil system on soft and dense soils.