Permeability of soil IS 2720

Cohesive soils such as clays have very low values of the coefficient of permeability k, while cohesionless soils such as clean sands and gravels can have a coefficient of permeability k that is a billion times larger than cohesive soils.
The reason is because of the size of the drainage paths through the soil. Open graded gravel has very large, interconnected void spaces.
At the other extreme are clay size particles, which produce minuscule void spaces with a large resistance to flow and hence a very low permeability.
In many cases, the determination of the coefficient of permeability k from laboratory tests on small soil specimens may not be representative of the overall field condition.
A common method of determining the field coefficient of permeability is through the measurements of the change in water levels in open standpipes. Although the type of soil is the most important parameter that governs the coefficient of permeability k of saturated soil, there are many other factors that affect k, such as:
1. Void ratio.
2. Particle size distribution.
3. Soil structure.
4. Layering of soil.
5. Soil imperfections or discontinuities.

Permeability ranges from 10-2 to 10-8 cm/sec

Comments

Post a Comment

Popular posts from this blog

Softening point IS 1205 1978

Hot the bitumen in oven or on hot plate at 75oc – 110oc above softening point say at 90oc + softening point of bitumen and pour it in the rings Balls weights 3.5 gms and dia of Ball is 9.5 mm After 30 min in air place it in beaker 600 ml and keep it in apparatus the temp of Distilled water should be 0oc and heat it at the rate of 5oc /min place the thermometer and note down the temp when balls touched the lower plate. For CRMB 55 the Softening point is 55oc For CRMB 50 the softening point is 50oc And For CRMB 60 the Softening point is 60oc For Bitumen having the Softening point above 80oc use Glysrine in place of water and the starting temp should be 35oc In IS 1205 1978 the water bath is written to perfotm the test first keep the beaker with sample in water bath for 15 min at 5oc and then allow to rise the temp at 5oc per min.
Read more

Shear Strength of concrete

Concrete subjected to bending and and shear stress is accopanied by tensile and compressive stress. The shear failure are due to resulting diagonal tension. The shear strength is generally 12 to 13 percent of compressive strength.
Read more