The angle of internal friction or angle of friction is a property of granular materials which has a simple physical interpretation, as it is related to the angle of repose or maximum possible angle for the slope of a set of said granular material. In any granular material, the angle of repose is determined by friction, cohesion and the shape of the particles; Therefore, in a material without cohesion and where the particles are very small in relation to the size of the whole, the angle of repose coincides with the angle of internal friction.

It is especially important in soil mechanics to determine both the bearing capacity and the slip resistance of sandy soil.

There are numerous procedures for determining the angle of repose, each producing slightly different results. The results are highly dependent on the exact methodology of the experimenter and as a result, data from different laboratories may not be comparable. Furthermore, the range of the bearing capacity of a terrain depends exponentially on the tangent of said angle:

So small errors in the determination of the angle lead to very different estimates of the bearing capacity. Alternatively, in many cases a measurement is usually made using an instrument called shear cell, whose measurement would be directly related to the bearing capacity.

Contenido

El ángulo de rozamiento interno a veces interviene en el diseño de equipos para el procesado de partículas sólidas. Por ejemplo, se puede usar para diseñar un silo de almacenaje o el dimensionado de una cinta transportadora para materiales granulosos. E igualmente en geotecnia y geología el ángulo de rozamiento interno es importante para determinar la estabilidad de taludes, la resistencia de una cimentación o para el cálculo del empuje de tierras.

En el transporte de graneles por mar, este valor es de fundamental importancia pues tiene estrecha relación con el valor del ángulo de rolido y el posible corrimiento de carga que afecta la estabilidad trasversal de la embarcación. La Organización Marítima Internacional (OMI) fija las normas para el transporte de graneles por mar.

antlion larvae

The antlion larva traps ants and other small insects by excavating a conical hole in loose sand, such that the slope of the hole is very close to the angle of repose of the sand.[1] So when a small insect prowls through the hole, its weight causes the sand to collapse inward, dragging it towards the center, where the antlion larva waits in wait.

Angle of internal friction of some materials

Here is a rough list of some materials with their angles.[2]​.

The angle of internal friction plays an important role in other areas of geotechnics and geology, including:.