The German Federal Waterways and Shipping Administration operates about 280 weirs, half of which are more than 50 years old. Many of these weirs will therefore need to be refurbished in the near future, even though budget resources are shrinking. An inflatable dam is a relatively new gate type, which enables savings to be made on the capital spending and maintenance costs. It consists of a multi-ply rubber membrane (Figure 1), is filled with air or water and clamped to the weir body with one or two fixing bars (Figure 2). Inflatable dams
have a number of advantages when compared with steel gates [2]:
- The design is simple and does not include any moving parts (hinges, bearings); there are no problems due to corrosion or sealing and no lubricants used, which might be harmful to the environment. Inflatable dams are not affected by settlements or earthquakes.
- Drive mechanisms, such as hydraulic cylinders, electrical actuators or chains, which require a great amount of maintenance are not needed. Inflatable dams are controlled by inflating or deflating by injecting and discharging air or water.
- The cost of recesses and reinforcement is low and the transfer of forces into the weir sill is evenly distributed. Major refurbishments are thus facilitated considerably, especially if the existing concrete structure has to be included.
- Inflatable dams can be operated safely and can always be deflated to prevent blocking. The membranes can be installed or replaced within a few weeks so that the construction times and periods for inspection and refurbishment are considerably reduced
