Soil permeability, or hydraulic conductivity, is the rate of the flow of water through soil materials, and it is an essential characteristic across a broad spectrum of engineering and earth science disciplines. Geotechnical and civil engineers, hydrogeologists, soil, and environmental scientists all use this information for projects such as structural foundations, embankments, earthen dams, flood management, effluent infiltration, and more. It’s no surprise that the porosity and permeability of soils are related. Factors that Affect Soil Permeability:

Soil voids create an easy path for the movement of water, but other factors like hydraulic gradient, soil type, texture, and particle size distribution also affect permeability.

Darcy’s law, which dictates all results from soil permeability tests, is an equation describing the movement of fluids through a porous medium. This equation defines the coefficient of permeability or hydraulic conductivity of soils, a ratio of fluid velocity through the soil matrix to the hydraulic gradient.

Soil Permeability tests take place under either constant head or falling head conditions:

  • Constant Head Test refers to an apparatus where the same relative elevation of the top of the water column (head pressure) remains over the sample throughout the test. It is a valid test for soils with a high rate of flow like sands and gravels, but also some clay soils.
  • Falling Head Test allows the head to decrease as water infiltrates the sample, diminishing the pressure over the course of the test. Falling head methods are generally limited to fine-grained soils.

Soil Permeability Testing Equipment:-

  1. Flexible-Wall Permeability Cells
  2. Constant Head Permeameters
  3. Constant/Falling Head Permeameters
  4. Compaction Permeameters
  5. Shelby Tube Permeameters
  6. Double-Ring Infiltrometers
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