Steel portable cofferdam launched with marine airbags
admin:admin time:2012-02-04
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The seventh cross-Yangtze River bridge of Wuhan City is the largest three-tower cable-stayed bridge with 616 meters of main span. This 4.7-billion-RMB bridge opened on January 2, 2011.
Eversafe Marine is proud of his own contributions to the bridge construction: successfully launched two portable steel cofferdams constructed to facilitate bridges piers construction with marine airbags.
Those two cofferdams weigh 2580 and 2800 tons. The biggest one measures by 57 m long, 35 m wide and 16 meters high, covers a twice time area of the basketball court and is higher than 5-floor building.
Small cofferdams are often launched into river by crane and winches but for more than 2,500 tons weight there are many limitations of deploying cranes to launch. Eversafe Marine as the professional engineering company was invited to research feasibility of cofferdam launching with air bags from natural dirt ground. If airbag launch method is possible then the cofferdam can be built on river bank completely which can save much investment and time.
After research and calculation Eversafe Marine believed the cofferdam launch with airbags is safe. To avoid any possible deformation of cofferdam and ground sink, Eversafe team designed the most safe launch plan from underlay of cofferdam to launch ramp angle adjustment.
When the launch time came, the cofferdam was moved forward 10 meters to near the water, then the pulling back ropes were cut down. At that time huge cofferdam began to move with rolling airbags by gravity slipping force, it splashed big spoondrifts when got into water at last floated by its own buoyancy smoothly. Then tugs towed cofferdam to its right position.
Cofferdam airbag launching is similar to ship launching but still there are some big differences. In most cases cofferdam launch is temporary launch so launch conditions can not be good. Cofferdam has a high gravity center position so people must control the maximum allowable tilted angle during the launching. When people have to launch the cofferdam with deficient water level there will be a big problem. And cofferdam has more water resistance when enter into water so the onward momentum should be bigger than vessel when it is launched.
Airbag launching technology is adaptable to all kinds of launch conditions so it is most suitable for temporary launch project. In the past two years Eversafe Marine launched more than 15 pieces steel cofferdams with marine air bags, saved clients more than three million RBM cost. Simple is the best, we believe more and more clients will benefit from our innovative airbag launching technology.
