Example Questions Related to Soil Phase Diagram

1) One cubic metre of wet soil weighs 19.80 kN. If the specific gravity of soil particles is 2.70 and water content is 11%, find the void ratio, dry density and degree of saturation.

Solution

Bulk unit weight, = 19.80 kN/m³

Water content, w = 11%

                                    = 0.11

Specific gravity of soil particles G = 2.70

                         

Unit weight of water, γw = 9.81 kN/m³

                       

            Void ratio, e = 0.485

 Degree of Saturation, S = 61.24 %

2) Determine the Water content, Dry density, Bulk density, Void ratio and Degree of saturation from the following data.

Sample size 3.81 cm dia. × 7.62 cm ht.

Wet weight = 1.668 N

Oven-dry weight = 1.400 N

Specific gravity = 2.7

Wet weight, W = 1.668 N

Oven-dry weight, Wd = 1.400 N

Solution

   

Specific gravity of solids, G = 2.70

3) A soil has bulk density of 20.1 kN/m³ and water content of 15%. Calculate the water content if the soil partially dries to a density of 19.4 kN/m³ and the void ratio remains unchanged.

Solution

Bulk unit weight, γ = 20.1 kN/m³

Water content, w = 15%

If the void ratio remains unchanged while drying takes place, the dry unit weight also remains unchanged since G and γw do not change.

New value of γ = 19.4 kN/m³

           

Hence the water content after partial drying = 10.86%

4) The porosity of a soil sample is 35% and the specific gravity of its particles is 2.7. Calculate its void ratio, dry density, saturated density and submerged density.

Solution

Porosity, n = 35%

         

Specific gravity of soil particles = 2.7