Innovations

The water bag system for controlling water-filled rubber dams is a Floecksmühle design and development. The water bag is an open control system ensuring easy and safe operation of the dam.

Using the water bag system may reduce the space requirement of the control system considerably, as the water bags of all spans are located in a single shaft. Therefore the water bag is very low-maintenance system.

Depending on the construction design and materials used, as well as on the relevant conditions on site the service life expectancy of a bladder is 30 years. Minor damage to the bladder may generally be repaired by cold vulcanization. When carried out properly, the repair of the damaged area is permanently durable.

Using the Floecksmühle safety systems may reduce the probability of damage to the bladder and increase its service life substantially.

The design and use of these safety systems are determined by the relevant application and local site conditions. In a personal meeting we will be pleased to give more detailed information about the specific execution of the dam at the customer’s site as soon as the relevant operational conditions are known.

Generally the following safety systems are available:

// FlexFlector ®

Overtopped FlexFlector® deflectors on the Maranon dam (Peru)

FlexFlector® - usage in Maranon (Peru)

When the rubber dam is overtopped, pressure variations tend to occur on the upstream and downstream sides of the dam structure due to changes in the flowing velocity and flowing direction of the overtopping water. In particular operating modes this may cause vibrations in the dam structure and thus friction between the bladder and the concrete surface.

The use of baffle blocks may reduce vibration amplitudes substantially while increasing the service life of the dam. In cooperation with the BAW (Federal Agency for Water Management) Floecksmühle developed such baffle blocks. From 2004 to 2006 Floecksmühle developed a system of what are called FlexFlector® deflectors of various shapes and sizes. In the summer of 2006 a live test was carried out on these deflectors. The measurements were attended and monitored by the BAW, Karlsruhe. The result showed that vibration amplitudes could be reduced to approx. 30% when using FlexFlector® deflectors.

The good experience from the development and the test show the need to provide FlexFlector® deflectors for reducing vibrations in overtopped rubber dams. Once the bladder is installed on site, the FlexFlector® deflectors are cold bonded to the bladder surface.

// Automatic deflation system

PADS (Pneumatic automatic deflation system) for water filled rubber dams

In the event of energy failure or malfunction of the control system an automatic safety system ensures deflation of the bladder as soon as the so-called safety retention level is exceeded.

Automatic deflation systems are used on both water-filled and air-filled rubber dams. Their activation is subject to the upstream water level and ensures controlled deflation of the rubber dam if and when the electronic control system does not work properly.

As soon as the upstream safety retention level is exceeded, the system is activated automatically. Depending on the given conditions, existing systems may be adjusted or customized solutions may be designed.

// Anti-abrasion protective layers

Bladder underlays protect the fully or partially deflated bladder against abrasion from friction on the surface of the dam structure. At the same time, the protective layer prevents roughening of the dam structure surface resulting from the water jet impact on the downstream side of the rubber dam. There is no need for additional treatment or smoothening of the concrete surface. Due to the elastic nature of the protective layer, it also prevents damage especially from large bed load.

Protective layer at Los Laureles (Honduras)

 

Eroded dam slab behind the protective layer

Building on the wide experience gained, Floecksmühle has developed rubber dams of a very easy-to-install construction design. The various components (mounting systems, bladder etc.) are preassembled and prepared to the maximum extent possible at our own workshop, allowing for in-depth quality checks of all parts before delivery to the client on the one hand, and speedy installation on the site on the other hand.

Detailed installation drawings and on-site support from supervisors (provided by Floecksmühle) make the building block system work well, also enabling the client’s own personnel to do the installation work with the assistance and training of experienced Floecksmühle staff.

This efficient and flexible system ensures high installation quality with significant savings in time.

Preparation of reinforcement frames and pipe supports at the workshop

 

FishFlector® prototype on a project in Switzerland

Over the past years the significance of ecological aspects has increased notably in the planning of rubber dams, while the issue of fish passes across dams is mostly unstudied as yet.

In this context Floecksmühle has developed what are called FishFlector® deflectors as a prototype for a specific project in Switzerland. The FishFlector® system consists of a continuous row of jet deflectors fixed to the bladder by vulcanisation.

The FishFlector® deflectors channel the water flow directly into the downstream reservoir so migrating fish do not get in contact with the concrete slab. The cushion of water forming on the downstream side of the rubber dam allows fish to make their way safely across the dam.