This part of IS 2720 specifies the test procedure for determining the consolidation properties of cohesive soils under one-dimensional loading. It provides methods for evaluating the magnitude and rate of consolidation, which are essential for predicting foundation settlement.
Describes the procedure for conducting one-dimensional consolidation (oedometer) tests to determine the compressibility and consolidation characteristics of soils.
Quick Reference Values
Minimum specimen diameter60 mm
Minimum specimen thickness20 mm
Minimum diameter to thickness ratio3
Standard load duration per increment24 hours
Standard load increment ratio (Δp/p)1.0
Key Formulas
Cv = (Tv * d^2) / t — Coefficient of consolidation (where d is drainage path)
Cc = (e1 - e2) / log10(p2/p1) — Compression Index
mv = (e1 - e2) / ((1 + e1) * (p2 - p1)) — Coefficient of volume compressibility
av = (e1 - e2) / (p2 - p1) — Coefficient of compressibility
Practical Notes
Always ensure porous stones are properly saturated before the test to prevent them from absorbing moisture from the soil specimen.
Careful sample extraction into the consolidation ring is critical; sample disturbance significantly alters the preconsolidation pressure and compression index.
Maintain a relatively constant room temperature during the test, as temperature variations affect water viscosity and thereby the rate of consolidation.