Question

When the effective pressure is smaller than pre-consolidation pressure, the final settlement is ____________

(a) \(ρ_f=Hlog_{10}  \frac{σ’}{σ’_0}\)

(b) \(ρ_f=H \frac{C_c}{1+e_o} log_{10}  \frac{σ’}{σ’_0}\)

(c) \(ρ_f=H \frac{C_S}{1+e_o} log_{10}  \frac{σ’}{σ’_0}\)

(d) \(ρ_f=H \frac{1}{1+e_o} log_{10}  \frac{σ’}{σ’_0}\)

I got this question in a job interview.

Query is from Consolidation Process in chapter One Dimensional Consolidation of Geotechnical Engineering I

Answer 1

The correct answer is (c) \(ρ_f=H \frac{C_S}{1+e_o} log_{10}  \frac{σ’}{σ’_0}\)

The explanation is: When the effective pressure σ’ is smaller than pre-consolidation pressure σp‘, the final settlement is given in terms of swelling index,

\(ρ_f=H \frac{C_S}{1+e_o} log_{10}  \frac{σ’}{σ’_0}.\)