RESEARCH IN DISTRIBUTION OF PRESSURE IN SOIL DEPTH UNDER WHEELS OF DIFFERENT MACHINES

As a result of climate change, a significant increase in population at global level and consequently of food needs, the soil is continuously subjected to the risk of degradation. One type of soil degradation is the artificial compaction, which is recognized by the European Union as a major problem for the environment and agriculture. Occurring as a result of the development of mechanized agriculture that involves the use of heavy machinery for agricultural works, often performed on soils with high moisture, compaction can reduce the agricultural production by up to 60 %. In Romania, artificial compaction affects about 6.5 million hectares of arable soil, and natural compaction is found on about 2 million hectares. Compaction is influenced by the factors such as the soil moisture, soil type, external load, tire inflation pressure, shape of the contact area between soil and tire, number of passes on the soil. The paper presents the results of experimental research conducted in the laboratory, which aimed to determine the distribution of stresses in the soil for various conditions. Wheels of two agricultural machines were tested at three inflation pressures: 100, 150 and 200 kPa. The compressive force on the wheel was applied by means of a 10 kN cylinder from the Hydropuls installation for testing in simulated and accelerated regime. The FlexiForce Tekscan force sensors have been mounted in the container at eight soil depths: 5, 10, 15, 20, 30, 35, 40 and 45 cm. Diagrams showing the variation of pressure in the soil at the tested depths were obtained for the applied force, showing that the pressure applied on the soil has uneven variation to a depth of 30-35 cm, and then follows a downward curve with increasing depth.