Patent – rubber dam with contour membrane

On April 01, 2021, we filed a patent application for a possible future development in rubber dam technology.  Patent application (A50233/2021) was submitted to the responsible authority.

The purpose is the targeted deflection of the spillway stream to utilise the energy of the water discharged via the rubber dam, thus deliberately avoiding energy conversion at the horizontal weir plate.

For this purpose, the classic rubber dam is covered by an additional membrane stretching from the upstream clamp to the desired position on the downstream side.

This membrane is freely strung laterally, with a gap to the weir cheek, to enable water on the underside of the weir to be drained off.

Due to water load, the diaphragm sags only with a “rope curve” under uneven loading, the sag being adjusted by the tensioning force.

This can be done on the one hand by changing the dam height, and on the other hand by changing the holding force on a movable roller bearing on the upstream or downstream side.

The relevant model tests are being carried out in cooperation with the Vienna Technical University and the company UpSurfDown GmbH.

Applications currently under development:

  • Regulating lock for ejector power plant – System ZT-Fritsch
  • Gravel locks with fish descent capability
  • Surf wave formation
  • Tidal weirs with alternating, double-sided weir loading

The role of Hydro Construct

For decades, there were no real alternatives to concrete and steel weirs. In recent decades, however, the development of rubber dam technology has rapidly accelerated. One of the pioneers, and today the European market leader in this field, is Hydro Construct based in Steyr, Upper Austria. With more than 110 successful installations and 37 years of practical experience, the company has unparalleled expertise in this field. It’s recipe for success is a mix of hydraulic engineering expertise, creativity, competent partners in the field of turbine construction, and ongoing optimisation research. With a firm belief that “standstill breeds stagnation”, both the standard and the functionality of the products are constantly adapted and further developed.

Hydro Construct GmbH has been setting its own records for years when it comes to expanding the dimensions of the flexible weir system, or rubber dam.

The main advantage of this system, compared to conventional weirs, is its use of very wide channels for reservoir control, without limiting the natural water flow by building massive structures across it. In 2012, for example, the longest rubber dam in Europe was constructed in Albania, with a length of 265 m at a height of 2.3 m; and in 2017 India’s longest rubber dam to date was designed in Uttar Pradesh with a length of 270 m at a height of 3.2 m.

Hydro Construct rubber dams can be used up to a damming height of 4.5 m. This is made possible by custom production of the membrane in one piece and corresponding width using a seamless vulcanising press. This height specification has already been tested for single-span installations in Turkey and France but has now been installed as a 4-span weir in Piedmont, Italy, in a town on the Po River with the resonant name of Casale Monferrato. With a combined width of 4 x 50 m, i.e., 200m in total, it boasts a regulating height of 4.3 m, achieving a European record with a dam area of over 800 m². Our latest order for the construction of a 360 m long and 3.10 m high air-filled weir in Bihar Province India, again sets new records with a damming area of over 1100 m². This plant is scheduled to be commissioned in the summer of 2022.

Finally, Hydro Construct rubber dams have recently been equipped with permanent sonographic crown height measurement, available on request. This enables a high level of control accuracy even for large reservoirs.