Saturday, 28 July 2018

Determination of Co-efficient of Permeability by Constant Head Permeameter

Co-efficient of Permeability by Constant Head Permeameter 

This test is suitable for coarse grained soils which are highly permeable.
The apparatus use for this test is called constant head permeameter. Fig (a,b) shows the diagrammatic representation of this test.

Determination of Co-efficient of Permeability by Constant Head Permeameter 
The sample of length 'L' & cross sectional area 'A' is subjected to a head 'h' which is kept constant (by over flows) during the progress of the test .
The test is performed by allowing flow of water through the sample and measuring the quantity of discharge (Q) in time 't' with the help of measuring jar . The value of co-efficient of permeability (K) can be computed directly from the Darcy's law .

We have from Darcy's law ,Discharge per unit time-
(q) = Q/t = K.i.A
or,  K = Q/t.i.A
or,  K = Q/A.h.t     
[where , i (Hydraulic gradient) =h/L]