UPSC Civil Service Exam Questions - Engineering

Q1:

A normally consolidated clay layer settles by 25 mm when the effective stress is increased from 15 kPa to 30 kPa. If the effective stress is later increased further from 30 kPa to 60 kPa, then the additional settlement would be

A 25 mm

B 50 mm

C 75 mm

D 100 mm

ANS:A - 25 mm

ΔH1=25mm
Δσ1= σ2-σ1~30-15=15N/mm2
Δσ2= 60-30~=30N/mm2

We know that: ΔH=mv.σ.h
ΔH1/ΔH2=mv.Δσ1.H/mv.Δσ2.h

ΔH1/ΔH2= Δσ1/Δσ2
25/ΔH2= 15/30
25/ΔH2= 0.5
25÷0.5= H2
50=H2~~~~~~H2=50mm.