In general, soil stiffness is determined by soil shear strength. The higher the soil stiffness is, the more fatigue damage may occur in the riser pipe, since vibration frequency and stress ranges will be higher. Secant soil stiffness is generally higher than tangent soil stiffness.

What are stiff clays?

The stiffness of a clay is largely an index of its moisture content. The current definition of ‘stiff’ relates strictly to consistency.

What are the 4 soil types?

OSHA classifies soils into four categories: Solid Rock, Type A, Type B, and Type C. Solid Rock is the most stable, and Type C soil is the least stable. Soils are typed not only by how cohesive they are, but also by the conditions in which they are found.