Drain Sizing: Difference between revisions

Latest revision as of 15:14, 11 July 2023

“The objective of filters and drains used as seepage control measures for embankments is to efficiently control the movement of water within and about the embankment. In order to meet this objective, filters and drains must, for the project life and with minimum maintenance, retain the protected materials, allow relatively free movement of water, and have sufficient discharge capacity. For design, these three necessities are termed piping or stability requirement, permeability requirement, and discharge capacity, respectively. The terms filters and drains are sometimes used interchangeably. Some definitions classify filters and drains by function. In this case, filters must retain the protected soil and have a permeability greater than the protected soil but do not need to have a particular flow or drainage capacity since flow will be perpendicular to the interface between the protected soil and filter. Drains, however, while meeting the requirements of filters, must have an adequate discharge capacity since drains collect seepage and conduct it to a discharge point or area. In practice, the critical element is not definition, but recognition, by the designer, when a drain must collect and conduct water. In this case the drain must be properly designed for the expected flows.”. ^[1]

Examples

Learn more about filters and drains for outlet works

Learn more good practices for pipe installation

Best Practices Resources

Filters for Embankment Dams, FEMA

Seepage Analysis and Control for Dams (EM 1110-2-1901), USACE

General Design and Construction Considerations for Earth and Rock-Fill Dams (EM 1110-2-2300), USACE

Trainings

On-Demand Webinar: Filters and Drainage Systems for Embankment Dams

On-Demand Webinar: Internal Drainage Systems for Embankment Dams

Citations:

↑ General Design and Construction Considerations for Earth and Rock-Fill Dams (EM 1110-2-2300), USACE, 2004

Revision ID: 7079
Revision Date: 07/11/2023

[USACE-1] General Design and Construction Considerations for Earth and Rock-Fill Dams (EM 1110-2-2300), USACE, 2004

[1]

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+[[Category:Seepage Analysis and Filter Design]]
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-“Adequate drainage should be provided under floor slabs for spillways and stilling basins to reduce uplift pressures. For soil foundations, a drainage blanket under the slab with transverse perforated pipe drains discharging through the walls or floor is generally provided, supplemented in the case of stratified foundations by deep well stems. Drainage of a slab on rock is usually accomplished by drain holes drilled in the rick with formed holes or pipes through the slab. The drainage blanket is designed to convey the seepage quickly and effectively to the transverse collector drains. It is designed as a graded reverse filter with coarse stones adjacent to the perforated drain pipe and finer material adjacent to the concrete structure to prevent the migration of fines into the drains. Outlets for transverse drains in the spillway chute discharge through the walls or floor at as low an elevation as practical to obtain maximum pressure reduction. Wall outlets should be 1 ft minimum above the floor to prevent blocking by debris. Cutoffs are provided at each transverse collector pipe to minimize buildup of head in case of malfunction of the pipe drain. Drains should be at least 6 in. in diameter and have at least two outlets to minimize the chance of plugging. Outlets should be provided with flat-type check valves to prevent surging and the entrance of foreign matter in the drainage system. For the stilling basin floor slab, it may be advantageous to place a connecting header along each wall and discharge all slab drainage into the stilling basin just upstream from the hydraulic jump at the lowest practical elevation in order to secure the maximum reduction of uplift of uplift for the downstream portion of the slab. A closer spacing of drains is usually required than in the spillway chute because of greater head and considerable difference in water depth in a short distance through the hydraulic jump. Piezometers should be installed in the drainage blanket and deeper strata, if necessary, to monitor the performance of the drainage system. If the drains or wells become plugged or otherwise noneffective, uplift pressures will increase which could adversely affect the stability of the structure (EM 1110-2-1602, EM 1110-2-1603, and EM 1110-2-1901)”. <ref name="USACE">[[General Design and Construction Considerations for Earth and Rock-Fill Dams (EM 1110-2-2300) | EM 1110-2-2300 General Design and Construction Considerations for Earth and Rock-Fill Dams, USACE, 2004]]</ref>
+“The objective of [[Filters and Drains | filters and drains]] used as seepage control measures for embankments is to efficiently control the movement of water within and about the embankment. In order to meet this objective, [[Filters and Drains | filters and drains]] must, for the project life and with minimum maintenance, retain the protected materials, allow relatively free movement of water, and have sufficient discharge capacity. For design, these three necessities are termed piping or [[stability]] requirement, permeability requirement, and discharge capacity, respectively. The terms [[Filters and Drains|filters and drains]] are sometimes used interchangeably. Some definitions classify [[Filters and Drains|filters and drains]] by function. In this case, filters must retain the protected soil and have a permeability greater than the protected soil but do not need to have a particular flow or drainage capacity since flow will be perpendicular to the interface between the protected soil and filter. Drains, however, while meeting the requirements of filters, must have an adequate discharge capacity since drains collect seepage and conduct it to a discharge point or area. In practice, the critical element is not definition, but recognition, by the designer, when a drain must collect and conduct water. In this case the drain must be properly designed for the expected flows.”. <ref name="USACE">[[General Design and Construction Considerations for Earth and Rock-Fill Dams (EM 1110-2-2300) | General Design and Construction Considerations for Earth and Rock-Fill Dams (EM 1110-2-2300), USACE, 2004]]</ref>
 ==Examples==
-{{Website Icon}} [[Filters and Drains|Learn more about filters and drains for outlet works]]
+{{Website Icon}} [[Filters and Drains | Learn more about filters and drains for outlet works]]
-{{Website Icon}} [[Pipe Installation|Learn more good practices for pipe installation]]
+{{Website Icon}} [[Pipe Installation | Learn more good practices for pipe installation]]
 ==Best Practices Resources==
-{{Document Icon}} [[General Design and Construction Considerations for Earth and Rock-Fill Dams (EM 1110-2-2300)]]
+{{Document Icon}} [[Filters for Embankment Dams | Filters for Embankment Dams, FEMA]]
+{{Document Icon}} [[Seepage Analysis and Control for Dams (EM 1110-2-1901) | Seepage Analysis and Control for Dams (EM 1110-2-1901), USACE]]
+{{Document Icon}} [[General Design and Construction Considerations for Earth and Rock-Fill Dams (EM 1110-2-2300) | General Design and Construction Considerations for Earth and Rock-Fill Dams (EM 1110-2-2300), USACE]]
 ==Trainings==
 {{Video Icon}} [[On-Demand Webinar: Filters and Drainage Systems for Embankment Dams]]
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 </br>
-Citations:
+{{Citations}}
-<references />
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