On a slope, what does the term angle of repose describe?

On a slope, what does the term angle of repose describe?

• A. The angle at which water runs off the slope.
• B. The maximum stable slope angle of a material before it walls or slides.
• C. The angle of blade setting.
• D. The angle at which soil dries out.

Answer: (B)

The angle of repose is the steepest slope at which a pile of loose material can remain stable without slumping or sliding. It reflects how the grains interact—friction, cohesion, particle shape and size, compaction, and moisture condition the stability. If the slope exceeds this angle, the material can no longer support itself and will avalanche or wall, making the slope unstable. This concept helps explain why earthmoving work must limit slopes to be at or below the material’s angle of repose. It isn’t about water runoff, blade settings, or how dry the soil is—that’s a different consideration.

The angle of repose is the steepest slope at which a pile of loose material can remain stable without slumping or sliding. It reflects how the grains interact—friction, cohesion, particle shape and size, compaction, and moisture condition the stability. If the slope exceeds this angle, the material can no longer support itself and will avalanche or wall, making the slope unstable. This concept helps explain why earthmoving work must limit slopes to be at or below the material’s angle of repose. It isn’t about water runoff, blade settings, or how dry the soil is—that’s a different consideration.