Question

A soil has a dry unit weight of 16.25 kN/m^3 and saturated unit weight of 20 kN/m^3. If the degree of saturation of soil is 50%, then its bulk unit weight will be ______

(a) 20.748 kN/m^3

(b) 17.628 kN/m^3

(c) 18.123 kN/m^3

(d) 19.246 kN/m^3

This question was addressed to me in an online interview.

This is a very interesting question from Functional Relationships topic in portion Preliminary Definitions and Relationships of Geotechnical Engineering I

Answer 1

The correct choice is (c) 18.123 kN/m^3

For explanation I would say: Given,

Dry unit weight γd = 16.25 kN/m^3

Saturated unit weight γsat = 20 kN/m^3

Degree of saturation S = 50% = 0.5

Bulk unit weight γ = γd + S[γsat– γd]

γ = 16.25 + 0.5[20-16.25]

γ =18.123 kN/m^3.