On the Angle of Interface Friction For Cohesionless Soils

Abstract

The angle of friction at the interface (or the skin friction) between cohesionless soil and another material is considered theoretically. It is pointed out that the angle of interface friction is upper-bounded by two different values. The first one is for the case when the interface is a velocity discontinuity between a mass of cohesionless soil and another material. In this case, the soil mass may or may not be at the limiting stress condition. This kind of friction angle may be independent of the strength and deformation properties of the cohesionless soil. The other one is for the case where a mass of cohesionless soil at the limiting stress condition moves solely due to its deformation along the interface without producing a velocity discontinuity. This kind of friction angle is a function of the strength and deformation properties of the cohesionless soil and the deformability of the material in contact with the cohesionless soil. Equations are given to evaluate the angle of soil interface friction from these properties as above.