Tuesday, 3 April 2018

Factors Affecting The Permeability

Permeability of a soil sample depends upon the following factors:


1) Size and shape of particles:- 


                                                  The permeability varies approximately as the square of the grain size. The permeability of coarse grained soil is inversely proportional to the specific surface of particles at a given porosity.


2) Properties of the pore fluid:-


                                                   The permeability is directly proportional to the unit weight of water and inversely proportional to its viscosity.Again the viscosity change with the change in temperature. Normally ,with the increase in temperature viscosity decreases and hence permeability increases.


3)Void ratio of soil:-


                                  The permeability (k) is directly proportional to c.e3/ (1+e), where 'c' is a factor and 'e' is the void ratio.Hence permeability decrease with decrease in void ratio & vice-versa.


4) Structural arrangement of soil particles :- 


                                                                         The permeability may vary with different geometric arrangement and shape of voids.


5)Entrapped air and organic impurities:-


                                                                    The permeability is greatly reduced if air is entrapped in the voids.Presence of organic foreign matter in soil mass also decreases the permeability .


6)Adsorbed water :-


                                  The adsorbed water surrounding the fine soil particles reduces the effective voids available for the passage of water and thereby reduces the permeability.

MORE-Permeability of Soil,Darcy's law-Limitation,Co-Efficient of Permeability,Importance of Study of Seepage Analysis

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