Consolidation Time Rate (Terzaghi)
How long a clay layer takes to reach a given degree of consolidation.
Example
You enter
- Target degree of consolidation U (%) 90
- Coefficient of consolidation cv (ft²/day) 0.1
- Drainage path Hdr (ft) 10
You get
- Time factor Tv 0.848
- T (days) 848
Checked against published worked examples from: University of the West of England (GeoCal).
Details, formula, and sources
ScopeTerzaghi 1-D consolidation: Tv = (pi/4)(U/100)^2 for U <= 60% else 1.781 - 0.933 log10(100-U), time t = Tv Hdr^2/cv. U 90%, cv 0.1 ft^2/day, Hdr 10 ft -> Tv 0.848, 848 days; U 50% -> 196 days (the decelerating curve). Hdr is half the layer for double drainage (a 4x time swing). The engineer of record governs.
Formula or tableTv = (pi/4)(U/100)^2 for U <= 60%, else 1.781 - 0.933 log10(100 - U); t = Tv Hdr^2 / cv.
Source and editionTerzaghi one-dimensional consolidation theory (time factor Tv), as compiled in Das, Principles of Geotechnical Engineering, by name.
Free accessThe Terzaghi time-factor series and the t = Tv Hdr^2/cv relation are standard published soil-mechanics results.
What governsEstimate. AHJ and licensed professional govern.
API field namesu_percent, cv_ft2_day, hdr_ft, tv, t_days
- Time factor Tv = (pi/4)(U/100)^2 (U <= 60%), else 1.781 - 0.933 log10(100 - U)Terzaghi consolidation theory
- Time t = Tv Hdr^2 / cvDas, Principles of Geotechnical Engineering
- Drainage path Hdr = full layer (single) or half (double drainage)scope of this tile