SOIL TENSIONS FROM DIFFERENT PRESSURES CAUSED BY FARM TRACTOR TIRES

摘要

The distribution of tensions caused by agricultural machinery depends on wheel load and inner tire pressure, as well as soil conditions. This study aimed to evaluate numerically displacements and tensions caused by tractor traffic on soil from the state of Ceara, Brazil. The rear tire weight (size 18.4-34 R1) on its contact area with the soil was 17.1 kN. Different inner pressures were considered in the numerical analysis based on the method of Finite Elements (96.5 kPa, 124.0 kPa, 151.0 kPa and 179.0 kPa), with their respective contact areas (0.2256 m(2), 0.1660 m(2), 0.1522 m(2) and 0.1393 m(3)). Our findings showed that vertical tensions on soil surface were nearly equal to tire inflation pressures. The lower pressure promoted less tension on the soil, showing that pressure reduction is necessary for further decreases on soil compaction up to a depth of 0.30 m. We also concluded that is essential to seek for solutions to reduce operating pressures, in order to decrease surface soil compaction derived from vertical and horizontal tensions.