Project: Statics of drystone walls

## Friction coefficient

The coefficient of friction, also called the coefficient of friction, is a dimensionless physical quantity. Between two bodies, the coefficient of friction defines the friction force in relation to the . Its value is required to calculate the friction or friction forceThe coefficient of friction μ is defined as the tangent of the friction angle θ.

Typical values of coefficients of friction for different types of rock:

Class / Coefficient of friction / Associated rock types.

Low friction / 0.36 -0.51 / shale (high mica content), slate, marl.

Medium friction / 0.51 - 0.67 / sandstone, siltstone, chalk, gneiss, shale

High friction / 0.67 - 0.84 / basalt, granite, limestone, conglomerate

## Reibungswinkel

The angle of friction denotes the angle that an inclined plane assumes with respect to the horizontal when a body lying on it just starts to move (static friction angle) or slides slowly at constant speed (dynamic friction angle, sliding angle). The angle of friction θ corresponds to the arctan of the coefficient of friction μ.

Typical values of friction coefficients for different rock types:

Class / Friction angle (dry) / Associated rock types

Low friction / 20° - 27° / shale (high mica content), slate, marl.

Medium friction / 27° - 34° / sandstone, siltstone, chalk, gneiss, slate

High friction / 34° - 40° / basalt, granite, limestone, conglomerate

The values apply to dry stone surfaces. If the surfaces are wet, the friction angle decreases sharply.

## Erddruck

Text Erddruck

Bei der graphischen Statik werden die Kräfte graphisch als Vektoren dargestellt. Die Darstellung der Kräfte durch Vektoren ermöglicht eine rein zeichnerische Ermittlung der Lage und Grösse der resultierenden Kräfte.

## Schwergewichtsmauer

Text Schwergewichtsmauer