Soil is usually represented in three phase system in which soil is usually consists of solid particles, water and air.
Here weight of air neglected are taken as zero and only weight of water and solid contributes to the total weight of the soil.
In saturated soil condition, Vv = Vw
In dry soil condition, Vv = Va
Basic Properties defined in soil are:
- Bulk Density(γ): γ=W/V
- Dry weight Density(γd) : γd=Ws/V
- Saturated Density(γsat) : γsat=Wsat/V
- Unit weight Density of solid soil(γs) : γs=Ws/Vs
- Water content(w) : w=Ww/Ws
- Specific Weight(G) : G=γs/γw
- Void ratio(e) : e=Vv/Vs
- Porosity(n) : n=Vv/V
There also relationship between these properties with the help of which any propertie can be computed if some of the properties are given. Here are some of the relationships between different properties:
- e and n:
If Vs=1 then e=Vv then V=1+e using these in the equation of n we get,
n = Vv / V ⇒ n = e / (1+e) - γd, γ and w:
w = Ww/Ws ⇒ 1 + w = (Ww+Ws) / Ws = W/Ws ⇒ 1+w = (W/V) / (Ws/V) = γ/γd - γ, G, e and Sr:
If Vs=1 then e=Vv and ew=Vv then Sr = ew/e
As,γ = W/V = (Ww+Ws)/V = (γw.Vw + γs.Vs)/V = (γw.ew + G.γw.1)/(1+e) = γw(G + e.Sr)/(1+e) - γd, G and e:
As,γd = Ws/V = γs.Vs/V = G.γw.Vs/V = G.γw/(1+e) - γsat, G and e:
As,γsat = Wsat/V = (Ww+Ws)/V = (γw.Vw+γs.Vs)/V = (γw.ew+G.γw.1)/(1+e)
In saturated condition ew = e
⇒ γsat = γw(e+G)/(1+e) - w, G, e and Sr:
As,w = Ww/Ws = γw.Vw/γs.Vs = (1/G).(Vw/Vs) = ew/G = e.Sr/G - γd, G and n:
If V = 1 then n = Vv ⇒ Vs = 1-n
As,γd = Ws/V = γs.Vs/V = γs.(1-n)/1 = G.γw.(1-n)
