How to calculate void ratio, porosity & degree of saturation?/ Finding void ratio, porosity & degree of saturation of soil.

 Eg:

 Calculate the void ratio, porosity & degree of saturation for the following given data.

Bulk unit weight of soil mass = 1.70, sp. gravity of soil grains = 2.75, water content = 24%

Calculation:

Given data:

Bulk unit weight = Ɣ = 1.70

Sp. gravity = G = 2.65

Water content = W = 24% = 0.24

To find:

Void ratio = e =?

Porosity = η =?

Degree of saturation = S =?

1. Void ratio:

 Ɣ = [ {Ɣw × G × (1 + W)} ÷ (1 + e)]

   Where, Ɣw = unit wt. of water = 1

1.70 = [ {1 × 2.65 × (1 + 0.24)} ÷ (1 + e)]

1.70 = [{3.286}  ÷ (1 + e)]

1+ e = [3.286  ÷ 1.70]

1 + e = 1.933

e = [1.933 - 1 ]

Void ratio = e = 0.933

2. Porosity:

η = [e ÷ (1 + e)]

   = [0.933  ÷ (1 + 0.933)]

  =0.483.

Porosity = η = 0.483

3. Degree of  saturation:

   S = [ ( W × G)  ÷ e]

      = [ ( 0.24 × 2.65)  ÷ 0.933]

      = 0.682

Degree of saturation = S = 68.20%

Thank you for going through these calculation steps❤. Have a good day 😄.

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