Inflatable rubber dam
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Inflatable rubber dams are cylindrical rubber fabrics placed across channels, streams and weir or dam crests to raise the upstream water level when inflated. The membrane is a multi-layer fabric made of synthetic fibre (usually nylon) and rubberised on one or both sides. The fabric is quite flexible and yet exhibits good wear-resistance characteristics. A layer of stainless steel mesh or ceramic chips can be embedded in the surface layer to reduce or prevent vandal damage.
The inflatable flexible membrane dams (IFMD, or rubber dams) were developed in the early 1950s - Flexidam - Imbertson. They are installed in stream and river beds, generally being bolted into a concrete foundation. They are used to divert water for irrigation, temporarily raising existing dams, flood control, water retention for aquifer recharge, reducing or preventing salt water intrusion into fresh water areas, protect low-lying coastal areas from tidal flooding, enabling fish passage past diversion works, by deflation, and for sewage retention/separation during flood events.
Inflatable dams can be filled with water, air or both. They are low pressure - typically 4 to 10 psi. The present trend suggests an increased use of air-filled membranes because they can be deflated or inflated more rapidly, and they are little affected by freezing conditions. Characteristic dimensions cover typically lengths of about 100 m with specially-made membranes up to 200-m wide, dam heights usually less than 5-m but some special designs might be up to 10-m high. The membrane is usually deflated for large overflows. It is however common practice to allow small spillages over the inflated dam. During overflows greater than 20% over-topping, vibrations might result from fluid-structure interactions, and the instabilities might damage or destroy the rubber membrane. Several failures were experienced (e.g. CHANSON 1996). In practice, a deflector (i.e. fin) is installed on the downstream face of the rubber dam to project the nappe away from the membrane, hence preventing rubber membrane vibrations.
There are more than 2000 inflatable rubber dams around the world. Durability can be excellent: recently, a 35-year-old dam in eastern Ontario, Canada was replaced, and while still functional in both freezing winter conditions when it was air filled, and water filled in summer, it was deemed to have served its useful life, and was replaced.
Examples of inflatable rubber dams
fin rubber dam
The balgstuw near Ramspol is an inflatable rubber dam. It is situated between the Ketelmeer and the Zwarte Water in the Netherlands. This dam is built to protect the villages against the rising water of the Ketelmeer. It is the biggest inflatable rubber dam of Europe.
The inflatable dam has three inflatable parts. The data of each inflatable part are:
- Situated 4,65 m under NAP
- Maximum height of the dam 3,55 m above NAP
- Height 10 m
- Length down 60 m, above 80 m
- Threshold width 15,4 m
- Length fabric 24,3 m
- Capacity dam: air 3.500.000 liter, water 3.500.000 liter
- Thickness fabric 1,6 cm
- Production Bridgestone, Japan
- Weight fabric 19,3 kg/m2
- Weight dam 33 tons
- Minimal lifetime fabric 25 year
- Closing time max. 60 min.
- Time to empty max. 180 min.
- Closing water level + 0.50 NAP
Adam T. Bower Memorial Dam
The Adam T. Bower Memorial Dam (formerly known as the Sunbury Fabridam) is the world's longest inflatable dam. The dam is located just below the confluence of the Western and Main Branches of the Susquehanna, between the towns of Shamokin Dam and Sunbury, Pennsylvania.
The dam is 2,100 feet (640 m) long. When it is raised in the summer time, it creates the 3,000 acre (12 km²) Lake Augusta, which is used for recreation. The dam and lake are part of Shikellamy State Park.
In 2001, the dam was renamed for Adam T. Bower, Chief Clerk of the Pennsylvania House of Representatives from 1967–68 and Director of Services during the Pennsylvania Constitutional Convention of 1967-68, by Act 2001-5 of the Pennsylvania General Assembly.
The longest single span (190m) rubber dam is located in Molino de Suso, Spain. Qingdao Hua Chen Industrial Science and Technology Company Limited has built the longest rubber dam with 3.7m high and 1,110m long in Asia. As the largest manufacture of rubber dam in China, Qingdao Hua Chen has built more than three thousand rubber dams all over the world.
- Ogihara, H.; Maramatsu, T. "Proc. 21st IAHR Congress, Melbourne, Australia": 600–604.
- "Adam T. Bower Dam". Archived from the original on August 24, 2005. Retrieved 2006-07-29.
- Finnerty, John (2005-05-07). "State to fix inflatable dam". The Daily Item. Archived from the original on 2007-09-30. Retrieved 2006-07-15.
- "HOUSE BILL No. 678 Session of 2001". Archived from the original on 2005-11-26. Retrieved 2006-07-29.
- Hubert Chanson (1996). Some Hydraulic Aspects during Overflow above Inflatable Flexible Membrane Dam, Report CH47/96, Dept. of Civil Engineering, University of Queensland, Australia, May, 60 pages (ISBN 0 86776 644 1).
- Hubert Chanson (1998). Hydraulics of Rubber Dam Overflow : a Simple Design Approach, Proc. 13th Australasian Fluid Mechanics Conference, Melbourne, Australia, 13–18 December, M.C. Thompson & K. Hourigan Ed., Vol. 1, pp. 255–258.