Typical Angle of Repose Values for Various Soil Types
Notation and Units
Critical Angle of Repose
The angle of repose or the critical angle of repose, of a granular material is the steepest angle relative to the horizontal plane which a material can be piled without slumping or the surface material sliding.
The internal angle between the surface of the pile and the horizontal surface (typically the surface which the material is piled on is known as the angle of repose and is related to the density, surface area, liquid content, shapes of the particles, and the coefficient of friction of the material under consideration.
The above values have been provided in the unit of angular degrees. As with all calculations care must be taken to keep consistent units throughout. A guide to Soil Types has been provided by StructX and additional information has been provided below.