All the basic Soil Water and Air Relations and Formulae, Three phase diagram II Soil Mechanics

Basic Soil and Water Relationships.
 Soil is considered a three-phase material, made of soil, water and air. The basic formulae used are written below. 

Sl No	Relationship in mass density	Relationship in unit weight
1	n = e/(1+e)	n = e/(1+e)
2	e = n/(1-n)	e = n/(1-n)
3	na = n ac	na = n ac
4	P= (G+Se)Pw/(1+e)	Y= (G+Se) Y w/(1+e)
5	Pd = GPw/(1+e)	Yd = G Yw/(1+e)
6	Psat = (G+e)Pw/(1+e)	Ysat = (G+e) Yw/(1+e)
7	P’ = (G-1)Pw/(1+e)	Y’ = (G-1) Y w/(1+e)
8	e = wG/s	e = wG/s
9	Pd = P/(1+w)	Yd = Y/(1+w)
10	Pd = (1-na)G Pw/(1+wG)	Yd = (1-na)G Y w/(1+wG)

Notations used: 
n = porosity, 
e = void ratio, 
na = air content,
P = Density,  Pd= dry density, 
Psat = saturated density, P' = submerged density
Y = Unit weight density, Yd = dry unit weight, 
Ysat = Saturated Unit weight, Y' = submerged unit weight
G = Specific Gravity
S = Saturation
w = water content

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