Question

saturated and dry unit weight of soil are 20 kn/m3 and 15 kn/m3 respectively. the water content of soil in the saturated state would be​

Answer 1

Answer:

Concept:

Bulk Unit weight (γb):

It is defined as the ratio of the total weight of soil to the total volume of the soil mass.

Water Content (w):

Water content or moisture content of a soil mass is defined as the ratio of the weight of water to the weight of solids (dry weight) of the soil mass.

It is denoted by the w and is commonly expressed as a percentage. The minimum value for water content is 0. There is no upper limit for water content.

Dry Unit Weight (γ­d):-

Dry unit weight is defined as the weight of soil solids per unit volume of soil. It is denoted by the letter symbol γd it has the unit of kN/m3.

It is used as a measure of the denseness of soil. A high value of dry unit weight indicates that more solids are packed in a unit volume of soil hence a more compact soil.

The specific gravity of solids (G):-

The specific gravity of solids is defined as the ratio of the unit weight of solids to the unit weight of water. It is denoted by the letter G and is a unitless quantity.

Note: The relationship between the degree of saturation, water content, specific gravity, and the void ratio is:

s × e = w × G

Calculation:

Given,

w = 25%, γ = 18.5 kN/m3, G = 2.65, γw = 9.81 kN/m3

We know, s × e = w × G

= =

18.5 =

e = 0.756

For fully saturated soil sample(s=1)

kN/m3

Air content:

Air content is defined as the ratio of the volume of air to the volume of voids. It is denoted by ac.

Porosity:

Porosity is defined as the ratio of the volume of voids to the total volume of soil. It is denoted by n. It varies between 0 and 1.

Percentage air voids:

Percentage air voids are defined as the ratio of the volume of air to the total volume of soil. It is denoted by n­­a.

Degree of Saturation:

The degree of Saturation of a soil mass is defined as the ratio of the volume of water in the voids to the volume of voids. It is denoted by S.

For a fully saturated soil mass Vv = Vw, hence S = 100%

For fully dry soil mass Vw = 0, hence S = 0%