Prediction of soil/tire interface contact pressure and the associated dry bulk density change along soil profile caused by wheel traffic by using the fem plaxis code

Research results have shown that soil compaction caused by agricultural machinery traffic can have an adverse effect on crop production. Various authors have tried to numerically model and investigate the degree of compaction in relation to machinery axle load, traffic, and the mechanical characteristics of the soil. Assuming a uniform soil/tire interface contact pressure distribution is one of the main problems with most of the FEM-based numerical models. Soil/tire interface contact pressure is not uniformly distributed; it varies depending on the soil properties and tire characteristics. We used PLAXIS to numerically model the soil/tire interface contact pressure perpendicular to the vehicle movement direction. The soil/tire interaction was modeled with a PLAXIS beam element of varying flexural rigidity placed on the soil surface loaded with a uniform pressure intended to simulate the load on the soil from the tire. Depending on the mechanical parameters of the specific soil and flexural rigidity of the beam element, different types of contact pressure distribution were obtained. A U-shaped soil/tire interface contact pressure distribution was obtained for a soft beam element while a parabolic type of distribution was observed for a rigid beam element. The results agree with what we have found in the literature. We also determined the dry bulk density profile in the soil caused by compaction using the PLAXIS simulation technique. These simulation results were compared to the measured field data available and it was found that the two are in agreement. Hence, beam elements with appropriate flexural rigidity can be used in machinery-traffic-based compaction modeling.