Question: A 4m deep clay layer is underlain by impermeable shale. A sample of clay from the layer is subjected to an appropriate increment of stress in a consolidation test giving the following results:
· Sample height at start of increment: 55mm.
· Sample height 2 minutes after start of increment: 53mm.
· Sample height at end of increment: 48mm.
If gravel fill is placed over the clay layer how long would it take for 80% consolidation of the clay to occur?