Plants jamming on water-saturated soils during contact with the supporting elements (feet) of walking machines

Abstract

Walking machines when working on waterlogged soils can be more efficient than wheeled machines. They provide increased ground passability and destroy the soil to a lesser extent. The paper discusses the results of studies of plant jamming by the feet of walking machines. Stamp tests of contact interaction of feet of various shapes with water-saturated soil were carried out. It was found that the greatest damage to the plant is obtained along the perimeter of the foot. This was the case at any depth of the footprint. Plants damaged by the foot, even in the case of small-sized feet, continued to grow after a period of depression. Wheeled and tracked movers, due to slipping and milling effect, are damaging plants to a higher extent. Mathematical modeling of the contact interaction of the foot with weak-bearing soil by the methods of finite element modeling has been carried out. Dimensional contact model for rigid feet of various shapes interacting with elastoplastic soil is formulated. The task was solved under conditions of large deformations of the supporting surface. The regularities of the stress-strain state of the soil in the zone of its contact with the foot under simple normal loading are obtained. Modeling shows that the greatest stresses occur along the perimeter of the foot, and the soil inside the perimeter is less loaded. This explains the nature of the plant jamming. Thus, the walking mode of movement in irrigated agriculture can provide lower plant jamming in comparison with traditional machines. Considering the smaller area of soil compaction and the absence of a continuous track, which is one of the causes of water erosion of the soil, it can be concluded that it is advisable to use small-sized feet.