Module 10
Consolidation and settlement with time
Why saturated clay settles slowly: excess pore pressure and its dissipation, the compression a load causes, and how that settlement unfolds over time.
What this module covers
- Explain consolidation as the time-dependent transfer of load from porewater to soil skeleton
- Distinguish immediate, primary consolidation and secondary compression settlement
- Use the e–log σ′ idealisation with Cc, Cr and the preconsolidation stress σ′c
- Compute primary settlement for normally and overconsolidated clay
- Derive the physical origin of the 1-D consolidation equation
- Use the time factor Tv and degree of consolidation U to find settlement with time
Lessons
Excess pore pressure, drainage, and the transfer of load from water to the soil skeleton.
Start lesson →Compression and recompression indices, preconsolidation stress, and the primary settlement equation.
Start lesson →The 1-D consolidation equation, the dimensionless time factor Tv, and settlement over time.
Start lesson →
Module checkpoint
Check what you have taken in
3 questions
Question 1
A normally consolidated clay 5 m thick has e₀ = 1.0 and Cc = 0.5. A wide load raises the effective stress from 50 kPa to 150 kPa. What is the primary settlement, in mm?
Question 2
At the instant a wide load is placed on a saturated clay, how is the total stress increment carried?
Question 3
A clay layer has final settlement 200 mm, cv = 1 m²/year, and drains from both faces with H = 4 m. How much settlement (mm) has occurred after 1 year? (Use U = √(4Tv/π) when Tv < 0.283.)