Module 10
Consolidation settlement and differential movement
The slow half of the problem — and the half that actually cracks buildings.
What this module covers
- Compute primary consolidation settlement honouring the stress history
- Explain why the preconsolidation stress changes the answer by a factor of two or more
- Use the time factor to predict how settlement develops, and the effect of drainage path
- Distinguish total from differential settlement and say which governs damage
Lessons
Stress history sets the magnitude; the drainage path sets the clock.
Start lesson →What actually damages buildings.
Start lesson →
Module checkpoint
Check what you have taken in
3 questions
Question 1
Two columns 8 m apart settle 35 mm and 15 mm. What is the angular distortion, expressed as 1/N — give N.
Question 2
A 4 m clay layer drains both ways with cv = 2 m²/year, so the drainage path is 2 m. Given that 90% consolidation needs Tv = 0.848, how long does it take, in years?
Question 3
Why does the preconsolidation stress have such a large effect on the calculated settlement?