APPLICATION OF UNSATURATED SOIL MECHANICS FOR AGRICULTURAL CONDITIONS

Agricultural engineers often draw upon the classical theories of soil mechanics in their study of agricultural soil behaviour. These theorie s are largely based on the assumption that the soil is saturated. In a n emerging theoretical framework, an unsaturated soil is considered to have four phases: solid, air, water, and contractile skin (the air-wa ter interphase). The contractile skin acts like a rubber membrane as i t induces a matric suction in the soil pores. Suction has been shown t o affect both strength and volume change characteristics of unsaturate d soils. The relationship between water content and matric suction (th e soil-water characteristic) becomes an important component of the uns aturated soil mechanics framework. In this paper, concepts and implica tions of these developments for some agricultural shear strength-based models are discussed. Experimental data highlighting these relationsh ips are also presented.