Correct Answer - Option 3 : 4
Concept:
Taylor Stability Number (Sn) = \(\frac{c}{{{F} × γ × H}}\)
Where C = cohesion, F = Factor of safety, γ = unit weight of soil, H = height of embankment
Calculation:
Given:
Sn = 1/40
c = 30 KN/m2
γ = 15 KN/m2
H = 20 m
Sn = \(\frac{c}{{{F} × γ × H}}\)
\(\frac{{30}}{{F × 15 × 20}} = \frac{1}{{40}}\)
F = \(\frac{40\ \times \ 30}{15\ \times \ 20}\)
F = 4
Then, Factor of safety with respect to cohesion = 4.