Types of EarthernDams

1. Homogenous Dams
2. Zoned Embankment type
3. Diaphragm type

1. Homogenous Embankment type

• The simplest type of an earthen embankment consists of a single material and is homogenous throughout.
• Sometimes a blanket of impervious material may be placed on the upstream face
• A purely homogenous section is used, when only one type of material is available.
• Used for *low to moderately high dams.
• A purely homogenous section poses the probably of seepage, and huge section is required to make safe against piping, stability etc.
• Due to this homogenous section is generally add with an internal drainage system. Such as horizontal drainage filter.

2. Zoned Embankment type

• In this type, they are usually provided with a central impervious core, covered by a comparative transition zone, which is finally surrounded by a pervious outer zone.
• The central core checks the seepage.
• The transition zone prevents piping through cracks which may develop in the core.
• The outer zone gives stability to the central impervious fill and also distributes the load over a large area of foundations.
• Transition filters are provided between the inner zone and the outer zone.
• This type of transition filters is always provided whenever there is an abrupt change in permeability from one zone to another.

3. Diaphragm type

• In this type, embankments have a thin impervious core, which is surrounded by earth or rock fills.
• The impervious core called Diaphragm is made of impervious soils, concrete or timber.
• It acts as a water barrier to prevent seepage through a dam.
• The diaphragm may be placed either at the centre as a centre vertical core or at upstream as a blanket.
• The diaphragm must also be betied to the bed or to very impervious foundation mater if under-seepage through the existing previous foundations must be avoided.
• The diaphragm type embankments are different from zoned embankment is depending upon the thickness of core.
• If the thickness of diaphragm at any elevation is less than 10 m or less than ht of the embankment above the corresponding elevation, the dam embankment is considered as ' Diaphragm type'.
• But if the thickness equals or exceeds this limits, it is considered as to be zoned embankment type.