A model of stress distribution and cracking in cohesive soils produced by simple tillage implements

The objective of this research was to describe the mechanical behavior of soil under the action of a tillage tool, with the purpose of finding a relation between the tool geometry and the resultant soil structure. The problem was solved using fundamental principles of soil mechanics and force equilibrium analysis. As a result, a mathematical model was developed which describes three stress zones within the cut soil volume: shear failure, tension failure, and no internal failure. The model was programmed into a computer to generate maps of normal and shear stresses to visualize the three failure zones. The model was tested by cutting soil with flat tillage tools in a laboratory soil bin, and it proved to provide reliable predictions of the pattern of soil shear and tension failure.