Foundation settlement calculator
One user-specified soil layer. This calculator does not estimate stress increase under a footing or select a stress distribution method. No default design criteria or 2:1 assumption is applied.
A QUICK WALKTHROUGH
How to use this tool
- Applied contact pressure q (kPa)
- Footing width B (m)
- Soil elastic modulus Es (kPa)
- Poisson ratio ν
- User-supplied elastic influence factor Is
- Compressible layer thickness H (m)
- Compression index Cc
- Initial void ratio e₀
- Initial effective vertical stress σ′₀ (kPa)
- Effective stress increase Δσ′ (kPa)
- Calculate settlement components
Model equations and references
Immediate component: Si = q·B·(1−ν²)·Is/Es, with compatible stress units and your supplied influence factor. Primary component for a normally consolidated layer: Sc = H·Cc/(1+e₀)·log₁₀((σ′₀+Δσ′)/σ′₀). The primary equation is given in FHWA GEC No. 6, Eq. 5-20 (https://www.fhwa.dot.gov/engineering/geotech/pubs/010943.pdf). An FHWA shallow-foundation reference describes elastic settlement equations and influence factors (https://www.fhwa.dot.gov/bridge/lrfdsteel/).
Scope and assumptions
One user-specified soil layer. This calculator does not estimate stress increase under a footing or select a stress distribution method. No default design criteria or 2:1 assumption is applied.
GOOD TO KNOW
Common questions
Does this establish that a foundation settlement is acceptable?
No. It calculates components for one user-defined layer; a qualified engineer must assess site conditions, serviceability criteria, stress distribution, and design.