Abstract:In response to the challenges posed by the sinking of agricultural walking wheels on wet and soft terrain, as well as the absence of a comprehensive interaction mechanics theory, the typical foot-terrain interaction models for pressure and shear mechanics were modified. Numerous foot-terrain interaction tests were conducted by using a universal testing machine to study the pressure and shear resistance-displacement of various foot designs on different types of wet and soft ground, including sand and soil with varying humidity levels. At the same time, the particle velocity field and motion trend of different types of foots on different wet and soft ground were investigated by means of EDEM discrete element simulation, which was used to observe the fine-scale behavior of wet and soft terrain. In the pressure test, the cylindrical foot was easier to sink compared with the rectangular foot. Combined with the simulation, the cylindrical foot was more likely to damage the soil structure under the foot, and the anti-subsidence performance of the rectangular foot was better than that of the cylindrical foot. The difference in intrusion resistance between rigid and rigid-flexible foots was not significant. The bearing capacity of sand was gradually increased with the increase of humidity, while the bearing capacity of soil was gradually decreased. In the shear test, the foot shear resistance of rigid cylindrical and rectangular foots under sand and soil with different humidity was related to the normal load, and both of them were increased with the increase of normal load. The foot shear resistance had little relationship with the medium humidity. Combined with the simulation, there was more soil accumulation in front of the foot in the process of foot shear, and the foot continuously pushed the soil above the slant, which needed the influence brought by the pushing effect to be further considered. Based on the pressure test data, the typical pressure-bearing model was modified, the subsidence-depth relationship of sand and soil with different humidity was supplemented. Based on the shear test data, the typical shear model was modified, and the shear resistance-displacement relationship was obtained by considering the influence of pushing soil. It can provide a design reference and theoretical basis for the development of a walking wheel foot on wet and soft terrain.
