Consider the following statements:
1. Soil with high void ratio has always more coefficient of permeability than the soil with lower void ratio.
2. Constant head permeability test is used for fine grained soil.
3. As temperature increases, the coefficient of permeability of soil also increases.
4. As the specific surface area of soil particle increases, the coefficient of permeability decreases
Which of these statements are correct?
Explanation:
Permeability is defined as the property of a porous material that permits the passage or seepage of water (or other fluids) through its interconnecting voids.
Factors affecting the permeability of soil can be studied using the following equation.
\(K = \frac{1}{Z}\frac{{{e^3}}}{{1 + e}}\;\frac{{{\gamma _w}}}{\mu }\;\frac{1}{{{S^2}}}\)
Where, Z = constant; μ = dynamic viscosity of water;
S = specific surface; γw = unit weight of water.
The factors affecting the permeability of soil can be summarised in the below-tabulated form:
Parameter |
Description |
Size of particle |
Higher the size of particle higher will be the permeability |
Specific surface area |
Higher the specific surface area lower will be the permeability |
Void Ratio |
Higher the void ratio higher the permeability |
Viscosity of water |
Higher the viscosity lower will be the permeability and we know that the viscosity of liquids (water) increases with a decrease in temperature and hence, permeability reduces. |
Degree of saturation |
Higher the degree of saturation higher the permeability |
Entrapped gases |
Higher the amount of entrapped gasses in soil mass lower will be the permeability |
Temperature:
Tests for Permeability