The angle of repose of a soil is the maximum angle which the outer face of the soil mass makes:
Try it first: pick an option, then read the explanation.
Correct answer: A. with the horizontal
Asked in SSC JE 27/01/2018 (Morning)
Detailed Explanation
Pour dry sand onto a flat surface and it forms a cone. However much more you pour, the slope of the cone stays at the same steepness, because grains roll down any steeper slope.
Why “with the horizontal” Is Correct
That limiting slope, measured with the horizontal, is the angle of repose. For a loose, dry cohesionless soil it is roughly equal to its angle of internal friction φ in the loose state.
Why the Other Options Are Wrong
- B. with the vertical: The angle is measured from the horizontal, not the vertical.
- C. with the perpendicular to the inclined plane of the soil: It is not measured from a perpendicular to the slope.
- D. none of these: Option (a) is correct.
Key Point
Angle of repose: measured from the horizontal; ≈ φ of loose dry sand.
Key Concepts for Students
- Typical angle of repose of dry sand: 30–35°.
- Cohesive soils can stand at steeper angles (even vertical) because of cohesion.
- Used for stockpiles and simple slope checks.
Practice more: this is question 16 in Earth Pressure and Retaining Wall MCQs – Part 2. Try the whole set and check every answer instantly.