SSC JE Civil Engineering 30-Oct-2020 Shift 2 Paper

Explanation:
Permeability depends on both soil properties and Fluid properties
The kozney – Carman equation is quite useful, it reflects the effect of factors that affect permeability
$\mathrm{k}=\frac{{\mathrm{\gamma }}_{\mathrm{w}}}{\mathrm{u}}+\frac{{\mathrm{e}}^3}{1+\mathrm{e}}{\mathrm{D}}_{10}^2$
Where,
${\mathrm{D}}_{10}$ is effective grain size
e is the void ratio
μ is viscosity , ${\mathrm{\gamma }}_{\mathrm{w}}$ is unit weight of water
a) Grain size: The coefficient of permeability includes D102, where D10 is a measure of grain sizeIf the void ratio is the same then permeability is more in coarse soil than in the fine soil
b) Void ratio: From the equation, it is clear that k ∝ ${\mathrm{e}}^2$
If the particle size is the same, then loose soils are more permeable than dense soils
c) Degree of saturation: Permeability is directly proportional to the degree of saturation
d) Particle shape: It is expressed in terms of specific surface area and permeability relates to specific surface area as ‘k ∝ 1/S2 ‘