Soil is formed by the disintegration of rocks. The relations between various physical properties of soil that is also called as Phase relations of soil or phase relationship of soil (Phase relations soil) is explained here.
Soil structure primarily consists of three phases namely the solid phase consisting of smaller that is very small fragments of rocks, liquid phase consisting of water, and air or gases as third phase.
The liquid that is the water and the gases will be filled in between the spaces in the solid mass of soil, these spaces in the solid mass of soil is called as voids.
Soil phase system (Phase relations soil):-
- Unsaturated soil mass consists of solids + water + air. It is in three phase system.
- Fully saturated soils are the soil in which all the voids are filled with water that is there will be no voids with air in it. Hence such fully saturated soil doesn’t have three phase system, but they will be having only solids and water and it will be 2 phase system.
- Fully dried soil do not have water in it. In such a case the soil phase system will be lacking of water in it, hence it will be a 2 phase system with solids and air.
Various relations and their definitions Phase relations soil:-
Void Ratio (e):-
Void ratio is defined as the ratio of volume of void of a soil mass to the volume of solids in the same soil mass.
- Void ratio can have a value greater than zero, but only sometimes void ratio value will be greater than 1.
- Void ratio for coarse grained soils is generally less than that for fine grained soil.
- When spherical grains are arranged in cubicle array, the maximum possible void ratio, e = 0.91.
- When spherical grains or arranged diagonally, the least void ratio, e = 0.35.
Porosity of soil mass is defined as the ratio of volume of voids to the total volume of soil mass expressed in percentage.
n = ( (Vol. of voids) / (Total Vol. of soil) ) X 100
Porosity of soil mass is also called as percentage voids.
Relation between porosity (n) and void ratio (e):-
n = ( e ) / (1+e)
where, n = porosity,
e = void ratio
Degree of Saturation (S):-
Degree of saturation of soil mass is defined as the ratio of volume of water in the soil to the volume of voids in the soil expressed in terms of percentage.
S = ( (Vol. of water) / (Vol. of voids) ) X 100
S = ( (Vw ) / (Vv) ) X 100
- The value of degree of saturation of soil will be between 0% and 100%
- For fully saturated soil the value of degree of saturation will be hundred percent.
- For dry soil the degree of saturation will be zero.
Water content/moisture content (w):-
The water content of the moisture content in the soil is defined as the ratio of the weight of water in the soil to the weight of solids in the soil expressed in terms of percentage.
w = ( (Wt. of water) / (Wt. of solids) ) X 100
- The value of water content in the soil will be greater than or equal to zero.
- sometimes the amount of water content or master content in the soil might be greater than hundred percent.
Specific gravity of soil ( G) :-
Specific gravity of the soil is defined as the ratio of weight of given volume of soil solids at a given temperature to the weight of an equal volume of distilled water at the same temperature.
It is denoted by G.
- As per is code standard, temperature for measuring specific gravity is 27 degree Celsius.
- For a given soil specific gravity remains constant.
- Generally specific gravity for inorganic soils lies between 2.60 to 2.85.