Civil Engineering Tools
BeamTrussMohr's CircleUnit ConversionsCentroidDeflectionBucklingConcreteRebarFE Prep

Retaining Wall Sliding Factor of Safety

Mediumretaining wallsliding
A wall has a vertical base force of 400 kN/m, a base friction angle of 25°, and a horizontal driving force of 120 kN/m. Ignoring passive resistance and adhesion, the factor of safety against sliding is most nearly:
  1. A0.78
  2. B1.17
  3. C2.33
  4. D1.55
Show solution

Answer: D. 1.55

Equation: factor of safety against sliding, FS = resisting force / driving force = N·tanδ / P. Values: N = 400 kN/m is the total vertical force on the base; it presses the base onto the soil and creates friction. δ = 25° is the friction angle between the base and the soil. P = 120 kN/m is the horizontal earth force pushing the wall. Passive resistance is ignored, as stated. Step 1: tan25° = 0.466. Step 2: resisting friction, F = 400 × 0.466 = 186.5 kN/m. Step 3: FS = 186.5 / 120 = 1.55. Using sin25° instead of tan25° gives 1.41. Dividing driving by resisting force inverts the ratio and gives a value below 1.
Practice this deckUntimed, one problem at a time, with your progress saved.

Related problems

Keep studying