ABSTRACT
The stability of soils is derived from the shearing strength. The ability of soils to support spread footings is directly proportional to their shearing strength. In a general manner, soils may be classified as granular or cohesive. Granular soils have internal friction resistance so that their shearing strength increases in relation to the normal pressure to which they are subjected. Purely granular soils have no cohesion. Clays found in the Appalachian basin are highly cohesive and have no angle of internal friction. They have a resistance to shearing due to their cohesive or molecular strength. Therefore, clays show that their shearing strength is the same regardless of the normal pressure to which they are subjected. Soil mixtures of clay and sand partake of both cohesive and internal friction resistance. Thus, most sands have some cohesion and most clays have some internal friction.
