19-04-2014, 01:10 PM
DETERMINATION OF PERMEABILITY OF SOIL BY CONSTANT HEAD METHOD
AIM
To determine the coefficient of permeability of the soil by conducting constant head method.
THEORY AND APPLICATION
The property of the soil which permits water to percolate through its continuously connected voids is
called its permeability .Water flowing through the soil exerts considerable seepage forces which has
direct effect on the safety of hydraulic structures. The quantity of water escaping through and beneath
and earthen dam depends on the permeability of the embankment and the foundation soil
respectively. The rate of settlement of foundation depends on the permeability properties of the
foundation soil.
APPARATUS
1. Permeability apparatus with accessories
2. Stop watch
3. Measuring jar
PROCEDURE
1. Compact the soil into the mould at a given dry density and moisture content by a suitable
device. Place the specimen centrally over the bottom porous disc and filter paper.
2. Place a filter paper, porous stone and washer on top of the soil sample and fix the top collar.
3. Connect the stand pipe to the inlet of the top plate. Fill the stand pipe with water.
4. Connect the reservoir with water to the outlet at the bottom of the mould and allow the water
to flow through and ensure complete saturation of the sample.
5. Open the air valve at the top and allow the water to flow out so that the air in the cylinder is
removed.
6. When steady flow is reached, collect the water in a measuring flask for a convenient time
intervals by keeping the head constant. The constant head of flow is provided with the help of
constant head reservoir
7. Repeat the for three more different time intervals