Tools · Soil mechanics
Three-phase diagram
Enter any three known soil properties. You get every other one with its formula and working, a phase diagram that redraws as you type, and where your soil sits against the saturation lines.
Known values
Fill in any three (leave the rest blank). Fill more and the tool checks they agree.
Worked examples
From lab readings
Fills in w = (M − Md) / Md and γ = (M / V)·γw. Add G (or one more value) to finish.
Settings
Phase diagram
e = 0.592 · n = 37.17% · S = 54.4% · w = 12.00%
Solve it step by step · start
What is given, what is to be found
Given: G, w, γ. To find: e, n, S, ac, na, γd, γsat, γ'.
Each step uses only values you already know (orange = given, green = found earlier) to find one new value. Tap any chip above to see what it means on the diagram.
All parameters
| Parameter | Formula | Value |
|---|---|---|
| G Specific gravity of solidsgiven | G = WsVs·γw | 2.680 |
| e Void ratio | e = VvVs = n1 − n = wGS | 0.5917 |
| n Porosity | n = VvV = e1 + e = 0.5921 + 0.592 = 0.3717 | 37.17 % |
| w Water contentgiven | w = WwWs = S·eG | 12.00 % |
| S Degree of saturation | S = VwVv = wGe = 0.12 × 2.680.592 = 0.5436 | 54.36 % |
| ac Air content | ac = VaVv = 1 − S = 1 − 0.5436 = 0.4564 | 45.64 % |
| na Percentage air voids | na = VaV = n·ac = e(1 − S)1 + e = 0.592 × (1 − 0.5436)1 + 0.592 = 0.1697 | 16.97 % |
| γ Bulk unit weightgiven | γ = (G + S·e)·γw1 + e = γd (1 + w) | 18.500 kN/m³ |
| γd Dry unit weight | γd = G·γw1 + e = γ1 + w = 2.68 × 9.811 + 0.592 = 16.518 | 16.518 kN/m³ |
| γsat Saturated unit weight | γsat = (G + e)·γw1 + e = (2.68 + 0.592) × 9.811 + 0.592 = 20.164 | 20.164 kN/m³ |
| γ' Submerged unit weight | γ' = γsat − γw = (G − 1)·γw1 + e = (2.68 − 1) × 9.811 + 0.592 = 10.354 | 10.354 kN/m³ |
How it is solved: every parameter depends on just three, G, e and S, so any three independent knowns fix the soil. The tool finds G = 2.680, e = 0.5917 and S = 54.36%, then works out the rest from the formulas above. Check: S·e = 0.3216 and w·G = 0.3216, so Se = wG holds.
Dry unit weight and water content
Each line is γd = Gγw / (1 + wG/S) for G = 2.680. No soil can plot above the zero air voids line; compaction curves always sit below it.