Landslides: Angles of Repose, Stability of Slopes, Material Strength
Angles of Repose
- steepest angle a slope can maintain without collapsing
- exact angle varies depending on the material the slope is made of
Stability of Slopes
- forces involved = driving force + resisting force
- driving force:
- gravity
- manifests as shear stress
- shearing: motion from side to side, but across a plane
- component on the force of gravity parallel to the slope
- resisting force:
- friction: resistance to sliding
- cohesion: how the material holds together
- together they are shear strength
- shear strength: slope’s ability to resist shearing motion
- resisting forces prevent slopes from failing
Average Material Strength
| %%Material%% | %%Friction%% | %%Cohesion%% | %%Shear Strength%% |
|---|
| most crystalline rock (igneous or metamorphic) | moderate | very high | high |
| most sedimentary rock | moderate | high to moderate | moderate |
| most sediment | low to moderate | low | low |