Question

If P is the vertical relation and ρ is the vertical deflection, then the modulus of sub-grade reaction is _______

(a) \(k_s=\frac{P}{ρ}\)

(b) \(k_s=\frac{1}{P}\)

(c) \(k_s=\frac{ρ}{P}\)

(d) \(k_s=\frac{P}{2ρ}\)

I had been asked this question in final exam.

This intriguing question originated from Design of Rigid Pavements in section Design of Flexible & Rigid Pavement of Geotechnical Engineering II

Answer 1

Correct answer is (a) \(k_s=\frac{P}{ρ}\)

Best explanation: The modulus of sub-grade reaction is defined as the intensity of pressure on the horizontal surface of a soil mass required to cause a unit settlement of surface.

∴ \(k_s=\frac{P}{ρ}.\)