MOSE Project
The MO.SE project ( = modulo sperimentale Elettromeccanico ) is currently a property under construction movable flood protection defense. It is at the three openings (Italian bocche ) of the Venice Lagoon and installed to protect the historic center of Venice from flooding (Italian: Acqua Alta). Similar barrages were successfully commissioned already in London ( Thames Barrier ) and Rotterdam ( Maeslant storm surge barrier ) in operation.
History
1984 first feasibility studies were prepared that had to be considered in addition to minimizing flood damage and the hydrogeological overall situation of the lagoon. For this purpose, was commissioned by the Venetian water authority in Padua a football field large basin in which all islands, all sandbars, tidal conditions and fairways of the lagoon were recreated detail. With the participation of well-known hydraulic engineers at the University of Padua, there were the effects of MO.SE on the mechanics of the water cycle rigorously analyzed.
In 1996 the project was approved by the government. On March 14, 2003 adopted Silvio Berlusconi, the Italian Prime Minister, the symbolic ground-breaking ceremony for the largest infrastructure project in Italy in the post-war period. But the political and economic participation alone Berlusconi in the project led to numerous discussions and a national topic of debate.
One of the biggest opponents of MO.S.E. Venice was the last mayor, Massimo Cacciari nonparty philosophy professor. Even after the start of construction he gave his resistance does not occur and the construction crews failed the cost -reducing usage of parts of the arsenal for the manufacture of major components of the locking mechanism. He stood all Acque in constant confrontation with Giovanna Piva, to October 31, director of the Magistrato. After the recent floods, the project is increasingly advocated.
Due to construction freeze and cuts, completion has postponed for two years. From the year 2016, be sure Venice and its lagoon from the constant flooding.
Financing
The estimated construction cost according to the current state of at least € 5.4 billion. But experts fear that they will achieve by 2014 around 6 billion euros. The annual maintenance costs are from the completion of approximately € 20 million. The project is financed mainly by state funds from Rome, a € 1.5 billion - loans from the European Investment Bank, funds Venice and UNESCO and numerous foundations.
Is carried out by the construction, the consortium Consorzio Venezia Nuova, an association of the 30 largest construction companies in Italy. Office of the Company is the Palazzo Morosini in the center of historic Venice Centro Storico. At this joint company belongs also the financial holding company Fininvest SpA, which is operated by the family Berlusconi.
Causes for the construction
Sea level rise and the sagging of the old town lead to the Centro Storico, which since 1987 a UNESCO World Heritage Site, is flooded more often.
Is responsible for the decrease in the Old Town, the removal of large amounts of groundwater and methane by the industry on the mainland. But the expansion of the fairways in the lagoon, the widening of bocche and pirate fishing are responsible. Fishermen with their catch baskets destroy the vegetation cover on the sea floor and thus the now faster flowing water masses can erode the sediments easier and flooding from the lagoon.
Operation and technique
When storm surges with a high water mark than 110 cm should be sealed with floating barriers in future the three lagoon entrances, the Bocca di Lido, the Bocca di Malamocco and the Bocca di Chioggia. The barrage consists of a total of 78 movable elements 18 at Chioggia, 19 at Malamocco and 41 at the Bocca di Lido. There, however, they are distributed between the respective banks and an artificially created island in the middle of the lagoon opening onto two lines. In the opening Lido - Treporti 20 and in the opening Lido - San Nicolo mounted 21 flood gates. The basic technique is not revolutionary new invention. The gates of large ship docks have long been moved by this principle. The flaps are large steel boxes that when they are in their slots on the ocean floor, are filled to the brim with water. If they are closed, press out the water with compressed air and the gates straighten up.
How it works also MO.SE, but with the subtle difference that all of the dimension ago is much more powerful and one of the gates incorporates an intelligent interior. For in the size of the individual gates (5 meters thick, 20 meters wide, 30 meters long with a weight of 250 t) and the forces which occur as the need to run and very accurate from the caissons. These are later with a 10- cm distance from each other in their anchorage. In any case, the individual elements may touch or even jam. To prevent this from happening, it is only pressed into its tip protruding from the top down behind a bulkhead air, so that there is a bubble. Thus, for each gate lift the front controls. The flaps are not simultaneously, but one after the other starting from the shore blown to have them as one after another rise out of the water.
The time frame from the first blowing up the correct positioning of the entire fortification is 30 minutes. The ideal position of the gates is achieved at a skew of 45 degrees and can make a difference of 2 m of water between the lagoon and the Adriatic Sea in the extreme. If it goes to the forecasts of the engineers, so the locking mechanism can usually go back down with the decline in flood after 4-5 hours. So that everything runs smoothly, the swimming flaps must be guided and supported solid. This task is performed oversized frames. These are made of reinforced concrete caissons, 14 meters high with a footprint of 50 x 60 meters per unit. Be attached to it later each 3 locking flaps at 3.20 meters high and 24 tons heavy duty hinges. In the rest position the flaps are completely immersed in the caissons. To ensure the waterway in the lagoon during the flood phase, the inlet is Malamocco ( for ships 370 m long up to 280 m in length and a draft of up to 12 meters ) equipped with a lock. Smaller ports and locks are also provided for the other two inlets.
One of the smaller ports on the Bocca di Lido is used as a pit for the manufacture of the caissons since its drainage and waterproofing in CSM process (Cutter Soil Mixing ). The CSM process turned out after extensive tests out as the ideal method of sealing the lagoon subsoil. This is to a depth of 28 meters from the unconsolidated sediments. This represents over 95% of components made of clay and fine sand with a grain size of 0.002 mm to 0.063 mm (so-called silt ). When CSM - methods of soil is under constant addition of suitable suspensions ( at MO.SE in the first step, bentonite) liquefied and bound in a second phase by the addition of cement suspension. In the CSM unit integrated tilt sensors simultaneously allowed the plane angle of the floor with a maximum deviation of 0.2-0.3 %.
The construction of the sheet pile walls the company HSP Hoesch sheet piling and Profil GmbH, a 100 % subsidiary of the German Salzgitter AG, moldings supplied in weight of 15,500 t. These were reinforced in view of the expected high water pressure in addition with special pipes with a total weight of 7,700 t of the company Europipe. When sealing the sheet piling also the CSM method was used successfully for the construction of the giant caissons the responsible engineers have developed a special procedure. In the later locks and docks at the Bocca di Lido giant stelae fields have been created. On the man-high concrete columns is the respective formwork. All precast concrete stay with this system at all times accessible from below. The finished caissons can be easily lifted with hydraulic presses and pulled by means of rollers for loading. With the heavy-duty lift in Europe, probably the greatest then up to 20,000 tons of heavy prefabricated components on the edge of the port are lowered into the water, because the MO.SE - frames reach their later floating berths. The caissons were aware of this, equipped with multiple air chambers that give them sufficient buoyancy forces. Tractor then pull the segments in place, where they are aligned with the help of GPS navigation aids and drained slowly. These floods are the air chambers. Additional weight and thus more stability to bring in individual cavities after weaning ballast in the form of gravel and scrap iron. On the front of the inspection paths are established, from which the lifting mechanism and the pneumatic lines can be maintained. To meet all environmental requirements, the fixtures must completely disappear under the sea floor, which - makes 14 meters deep and 50 m wide trenches required - transverse to the fairway. Just as the predetermined natural water cycle between the lagoon and the Adriatic Sea is not hindered. These channels are now largely completed and consolidated. This required large amounts of sand and silt to be dredged, about twice as much as the volume of the Great Pyramid. The mounting surfaces for the caissons have been exacerbated by 40 meter long piles. Right and left of the trenches were mounted on the seabed geotextile. The aim of Sedimentabtrag be prevented by the flow into the lagoon entrances. In Malamocco, the main access for large ships in the lagoon, the barrier is 14 m below sea level.
1,500 professionals work at the moment on the different construction sites and in front of the lagoon.
So far, Venice did not need any technical assistance to overcome height differences in the fairways. This will change with the lock systems from 2016 but fundamentally. For this purpose, a driving simulator was developed, pilots, headed by Mr. Lauro Celentano be prepared for the new challenges to the already. After just " walking speed " is allowed in the field of locks, created a dangerous drift for large tanker Malamocco. The culprit is the bora, a cold and gusty fall wind from the northeast (Croatia and Dalmatia ) with peak speeds up to 250 km / h offer the enormous masses of ships at low speed a huge attack surface.
Film
- Project Megabau / Gigantic. Venice flood barriers. (OT: . Venice Flood Gates ) Documentary, Canada, 2009, 45 min Written and directed by Karen Pinker, Production: Barner - Alper Productions, Discovery Channel Canada, series: Project Megabau (OT: Mega Builders ), German First broadcast: February 3, 2009 at Discovery HD, Summary of fernsehserien.de.