Example 2: A 3 m thick clay layer in the field under a given surcharge will undergo 7 cm of total primary consolidation.If the first 4 cm of settlement takes 90 days, calculate the time required for the first 2 cm of settlement.

Solution:

Total consolidation = 7 cm
For 4 cm settlement, U₁ = 4/7 x100 = 57.14%
For 2 cm settlement, U₂ = 2/7 x 100 = 28.57%
t₁ = 90 days.