Hydraulic fill

Hydraulic fill is a means of selectively emplacing soil or other materials using a stream of water. It is also a term used to describe the materials thus emplaced.^[1] Gravity, coupled with velocity control, is used to effect the selected deposition of the material.

Borrow pits containing suitable material are accessible at an elevation such that the earth can be sluiced

to the fill after being washed from the bank by high-pressure nozzles. Hydraulic fill is likely to be the most economic method of construction. Even when the source material lacks sufficient elevation, it can be elevated to the sluice by a dredge pump.

In the construction of a hydraulic fill

Stoke's Law

) as the flow velocity is reduced towards the center of the dam. This fine material forms an impervious core to the dam. The water flow must be well controlled at all times, otherwise the central section may be bridged by tongues of coarse material which would facilitate seepage through the dam later.

Hydraulic fill dams can be dangerous in areas of seismic activity due to the high susceptibility of the uncompacted, cohesion-less soils in them to liquefaction. The Lower San Fernando Dam^[2] is an example of a hydraulic fill dam that failed during an earthquake. In these situations, a dam built of compacted soil may be a better choice.

Poorly built hydraulic fill dams pose a risk of catastrophic failure. The Fort Peck Dam is an example of a hydraulic fill dam that failed during construction where the hydraulic filling process may have contributed to the failure.^[3]

Hydraulic fill is also a term used in

stopes

in a slurry by boreholes and pipes to stabilize the voids.

References

^ "Initiating Hydraulic Fill Projects" (PDF). International Association of Dredging Companies. Archived from the original (PDF) on 4 January 2014. Retrieved 16 December 2013.
^ "The Lower San Fernando Dam" (PDF). Archived from the original (PDF) on 16 December 2013. Retrieved 16 December 2013.
^ French, Brett. "Fort Peck Dam damage from 2011 being repaired". The Bismarck Tribune. Retrieved 16 December 2013.

[1] "Initiating Hydraulic Fill Projects" (PDF). International Association of Dredging Companies. Archived from the original (PDF) on 4 January 2014. Retrieved 16 December 2013.

[2] "The Lower San Fernando Dam" (PDF). Archived from the original (PDF) on 16 December 2013. Retrieved 16 December 2013.

[3] French, Brett. "Fort Peck Dam damage from 2011 being repaired". The Bismarck Tribune. Retrieved 16 December 2013.

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