SOIL MECHANICS OF AGRICULTURAL SOILS

Abstract

Soil mechanics has been developed to solve civil engineering problems in which compact soil is caused to fail at relatively low stress levels, and it is therefore applicable to primary tillage operations like ploughing. However, the much more important agricultural problem of the compaction of loose soils by the relatively high stresses induced by rolling and slipping tyres needs a new theoretical basis. The ideas of critical state soil mechanics provide an integrated mathematical system comprising three models describing elastic, brittle, and plastic compressible behaviour. The latter component is new and provides a means for applying plasticity theory to the problem of soil compaction. The theory also provides a means for determining which is the appropriate mathematical model to use. The paper attempts to describe these new ideas in soil mechanics in terms that are intelligible to soil scientists in general. Soil mechanics has been developed to solve civil engineering problems in which compact soil is caused to fail at relatively low stress levels, and it is therefore applicable to primary tillage operations like ploughing. However, the much more important agricultural problem of the compaction of loose soils by the relatively high stresses induced by rolling and slipping tyres needs a new theoretical basis. The ideas of critical state soil mechanics provide an integrated mathematical system comprising three models describing elastic, brittle, and plastic compressible behaviour. The latter component is new and provides a means for applying plasticity theory to the problem of soil compaction. The theory also provides a means for determining which is the appropriate mathematical model to use. The paper attempts to describe these new ideas in soil mechanics in terms that are intelligible to soil scientists in general. © Williams & Wilkins 1977. All Rights Reserved.