Soil Phase Relations (Void Ratio, Porosity, Saturation)

The three-phase makeup behind every settlement and bearing calc, made explicit.

Run the calculator

Example

You enter

You get

Details, formula, and sources

From the total unit weight, water content, and specific gravity Gs, the dry unit weight gamma_d = gamma/(1 + w), void ratio e = Gs gamma_w/gamma_d - 1, porosity n = e/(1 + e), and saturation S = w Gs/e. A 120 pcf soil at 15% and Gs 2.70 gives gamma_d 104.3 pcf, e 0.62, n 0.38, S 66% - the void ratio a consolidation needs, the saturation that says how much air is left to squeeze out. gamma_w = 62.4 pcf; enter Gs. An engineering aid; the soil test data govern.

gamma_d = gamma/(1 + w/100); e = Gs gamma_w/gamma_d - 1; n = e/(1 + e); S = w Gs/e. (gamma_w = 62.4 pcf)

The soil three-phase relations - dry unit weight, void ratio, porosity, and degree of saturation - as compiled in the Das and NAVFAC geotechnical references, by name.

The soil phase relations are public geotechnical results; NAVFAC DM-7 is public-domain and free online.

Estimate. AHJ and licensed professional govern.

Field names used by the API: gamma_pcf, w_pct, gs, gamma_d_pcf, e_ratio, n_porosity, s_pct

Related tools