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

Abstract

Semi-empirical traction models utilize soil parameters estimated from ASABE cone 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. Rectangular estimated tire-soil shape and a contact area of 484 cm2 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/m3 soil bulk density (66% of Proctor density) and 1.41 Mg/m3 soil bulk density (75% of Proctor density) initial conditions using circular, rectangular, and square plates, each at three scaled areas (λ = 0.5, λ = 0.25, and λ = 0.125, where λ = 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 λ = 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 λ = 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.