The Nature of Soil Failure as Applied to Agricultural Engineering

Abstract

The failure phenomena associated with tine implements in agricultural soils were observed. The observed nature of failure was found to depend on the type of soil, the soil moisture content and tine dimensions. Based on the observations in clay and sand, the failure mechanisms were classified into five distinct types, namely, Collapse, Fracture, Chip-forming, Plastic Flow and Frictional Flow. The Collapse and Fracture failures were cyclic phenomena, and the corresponding draft forces were perfectly cyclic when measured accurately. The Chip-forming, Plastic Flow and Frictional Flow were all steady-state phenomena, and the corresponding draft forces were steady-state. In all cases, the mechanisms of failure did neither resemble those prescribed by passive earth preesure theories nor adequately predict the draft forces encountered by agricultural tines.