About this tool Estimate the coefficient of consolidation (cv) from liquid limit using the US Navy (1971) correlation. This gives an order-of-magnitude estimate of cv when no oedometer test data is available — useful for preliminary settlement rate calculations.
Separate estimates are given for virgin compression (normally consolidated) and recompression (overconsolidated) stress ranges. Recompression cv is typically 5× higher than virgin compression cv.
Reference: US Navy Design Manual NAVFAC DM-7.1, Soil Mechanics (1971).
How to use this tool 1. Enter the liquid limit (LL) — from Atterberg limit testing per BS 1377-2.
2. Select the stress state — virgin compression for NC clays, recompression for OC clays.
Technical information log₁₀(cv) = 1.87 - 0.0274 × LL
where cv is in ×10⁻⁴ cm²/s (virgin compression)
For recompression: cv ≈ 5× the virgin compression value (upper bound of US Navy chart)
Conversion: 1 ×10⁻⁴ cm²/s = 0.3154 m²/year
Limitations This is an order-of-magnitude estimate only. cv varies by 2–3 orders of magnitude for soils with the same liquid limit. Always use oedometer test data for design.
The correlation is based on empirical data from a range of clays. It may not be reliable for unusual soils (organic, volcanic, cemented).
cv varies with stress level, strain range, and drainage conditions. A single value does not capture this complexity.
Revision history 16 June 2026: Initial release
Disclaimer This tool is provided for educational and general information purposes only. It is not a substitute for professional engineering advice, design or verification.
Diggy and its contributors are not licensed engineering consultants and no results generated by this tool should be used directly for construction, design or safety-critical decisions.
All values and outputs are based on published empirical correlations and should be independently checked and confirmed by a qualified geotechnical engineer before use.
By using this tool, you accept full responsibility for how you interpret and apply the information provided.
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