What are the role of filter in earthen dam?

Earth dams are constructed to store or divert water. A filter can keep the top How line or phreatic line well within the body of dam. As the phreatic line follows a parabolic shape, there is some minimum length of downstream drainage filter to prevent the downstream slope from the softening due to seepage.

Do dams have filters?

Do Dams Need Filters? All modern embankment dams (including tailings dams) should have engineered filters and drains to prevent seepage-related failures. Many embankment dams in the United States do not have properly designed filters.

How do you prevent failure of earthen dam?

Actions such as using sandbags to increase freeboard and prevent overtopping, using riprap to prevent erosion to the dam structure, or applying a geotextile filter fabric to combat piping are all examples of emergency intervention techniques that can be used to try to save a dam from a total failure.

What is inverted filter in dams?

Inverted filter. The inverted filter consists of one or more layers of graded coarse-grained, free-draining material over less pervious soil. It is used to prevent dams from failing by water piping through the foundation.

What is phreatic line in earth dam?

The top flow line of a saturated soil mass below which seepage takes place, is called the Phreatic line. Hydrostatic pressure acts below the phreatic line whereas atmospheric pressure exists above the phreatic line. For an earthen dam, the phreatic line approximately assumes the shape of a parabola.

What is chimney drain?

Chimney drains are vertical applications of free-draining material typically installed within an embankment and designed to intercept and control water seepage. J•DRAIN drainage composites are engineered to capture water and reduce hydrostatic pressure while efficiently channeling the water away.

What is rock toe in earth dam?

Rock-toe. It is a zone of free draining material consisting of cobble size material provided at the downstream toe of an earth dam. The principal function of a rock-toe is to facilitate drainage of water and protect the lower part of the downstream slope Page 6 from tail water erosion.

What is hydraulic failure in earthen dam?

This review highlights the hydraulic failure of earthen dams and embankments, emphasizing on the piping and overtopping phenomena. Piping failures are mostly attributed to the uncontrolled seepage or the absence of suitable zonation of materials and filters in earthen dams.

What are the reasons of hydraulic failure of earthen dam?

Causes of Failure of. Earthen Dams.

Why inverted filter is used in some for dewatering?

it helps to protect coastal area from erosion due to coastal waves. it also helps to maintain the stability of earthen dams.

Why are phreatic lines important?

This line separates a saturated soil mass from an unsaturated soil mass. It is not an equipotential line, but a flow line. For an earthen dam, the phreatic line approximately assumes the shape of a parabola.

What is sloughing of earthen dam?

IF the downstream toe of dam gets saturated by piping or any seepage action, it will get eroded and forms small slide or small slump. The slump will create steeper face which again gets eroded due to seepage and form slump again. This progressive removal of saturated soil is called sloughing.

What is the function of filter in earth fill dam?

The filter in the dam reduces the pore water pressure at the down-stream face of the dam, thereby the stability of the dam gets increase. Filter also controls the piping action to a great extent by checking the migration of soil particles. The down-stream drainage systems used in the earth fill dam are of following three types:

How is down-stream drainage performed in earthen dams?

The down-stream drainage is performed by providing the filter materials in the earthen dam. The nature of filter materials should always be more pervious than the general fill materials. The filter in the dam reduces the pore water pressure at the down-stream face of the dam, thereby the stability of the dam gets increase.

How do you control seepage in an earth dam?

Seepage control measures in Earth Dams Providing drainage filters is the best method to prevent seepage. Filters are provided for the free discharge of water and prevent piping and heaving. Drainages are used to reduce the pore water pressure inside the embankment and foundation soil.

What is an earthen dam?

The dam which is constructed fulfilled by the earth is known as the earthen dam. The earthen dam is constructed by different layers of soil. The layers of the soil of the earthen dam are then compacted by sheep’s foot rollers, tamping rollers, heavy pneumatic tired rollers, earth-hauling equipment, or vibratory rollers.