Example 1: A 3 m thick layer of saturated clay in the field under a surcharge loading will achieve 90% consolidation in 75 days in double drainage conditions. Find the coefficient of consolidation of the clay.

Solution:

As the clay layer has two-way drainage, H = 1.5 m = 150 cm
t₉₀ = 75 days = 75 x 24 x 60 x 60 seconds

For 90% consolidation (U = 90%)

T₉₀ = 0.848