Soil Phase Relationships Calculator: Unit Weights, Void Ratio, Porosity, Water Content and Saturation
The soil mechanics basics: weights and volumes of soil.
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How this calculator works
Enter Gs, the void ratio and the degree of saturation.
The calculator applies the phase relationships.
It gives the water content, the porosity and the unit weights.
Formulas used
- w = \frac{Se}{G_s}
- \gamma = \frac{(G_s + Se)\gamma_w}{1 + e}
- \gamma_d = \frac{G_s\gamma_w}{1 + e}
- n = \frac{e}{1 + e}
Worked example
With the default numbers in the calculator above:
- Water content: 15.849 %
- Porosity: 0.41176 (41.18 %)
- Bulk (moist) unit weight: 17.716 kN/m3
- Dry unit weight: 15.292 kN/m3
- Saturated unit weight: 19.331 kN/m3
- Submerged (buoyant) unit weight: 9.5215 kN/m3
- Density of the moist soil: 1805.9 kg/m3
Change the numbers in the calculator to see the full working, every step, for your own case.
Common questions
What is the void ratio?
The volume of the voids divided by the volume of the solid particles.
What is the difference between porosity and void ratio?
Porosity is the voids as a fraction of the total volume. The void ratio is the voids as a fraction of the solids volume.
What is the submerged unit weight?
The saturated unit weight minus the unit weight of water. It is the weight that counts in soil below the water table.
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Further reading: Any soil mechanics or geotechnical engineering text (soil phase relationships).
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