Properties of Soil Formula – Soil Mechanics

1. Water Content

where ,

W_w = Weight of water

W_s = Weight of solids

Note – There can be no upper limit to water content i.e. w≥0

2. Void Ratio

where ,

V_v = Volume of voids

V_s = Volume of solids

Note – though size of individual void of coarse grained soil is more , total volume of voids in fine grained soil is more

in general case there is no upper limit for void ratio . i.e. e>0

3. Porosity

where ,

V_v = Volume of voids

V = Total Volume of soil

Note – 1. Porosity cannot exceed 100% i.e. 0

2. in comparison to porosity , void ratio is more frequently used because volume of solids remains same , whereas total volume changes

4. Degree of Saturation

where ,

V_w = Volume of water

V_v = Volume of voids

Note – 1. Range of Degree of saturation. 0≤S≤100

2. For perfectly dry soil – S=0

3. For Fully saturated soil – S=100%

4. Air Content

where ,

V_a = Volume of air

where S_r= Degree of saturation

5. Percentage Air Void

where ,

V_a = Volume of air

5. Unit Weight

(A) Bulk unit Weight (γ)

Bulk unit weight is total weight per unit volume

(B) Dry Unit Weight (γ_d)

Dry unit weight is the weight of soil solids per unit volume

Note – Dry unit weight is used as a measure of denseness of soil . more dry unit weight means more compacted soil

(C) Saturated Unit weight (γ_sat)

Saturated unit weight is the ratio of total weight of fully saturated soil sample to its total volume.

(C) Submerged Unit weight or Buoyant unit weight (γ^′)

Submerged unit weight is the ratio of submerged weight of soil solid per unit volume