Heavy Lifting and Transfer

Dawson airbag heavy lifting and transfer solutions are cost effective and flexible. This technique needs only compacted ground and minimum facilities that is specially suitable for temporary heavy lift and transfer projects. 

Dawson heavy lifting bags are the most strong bags in the world, one piece bag can lift 300-500 tons weight to 50 cm height. Another peerless character of our lifting bags is they can roll steadily with the load. So Dawson heavy lifting bags are especially suitable for huge structure lifting and relocation.

The common mega structures had been successfully lifted and moved by airbags include concrete caissons,  pumphouses ,steel cofferdams, bridge blocks and tanks. All of them have high structure strength and wide bottom. Also there are some special objects had been relocated by airbags such as water diversion pipes and statues. 

  

  Pump house launched with airbags           Huge statue relocated by Dawson Marine

In China Dawson Engineering company has moved 200 pieces caissons whose maximum weight reaches 5,000 tonnes one piece. Regarding cofferdams, Dawson has successfully launched 2,700 tonnes box type and 2,200 tonnes double-wall round one. 

Solution Advantages 

Saving : Moving caisson with airbags can cut off 70% budget comparing with trolley method.

Safe:  Airbags have big contact area with transported object, the low reaction force is good for structure safety.

Convenient:  Air bags can move structure strightly in line or steer structure to anywhere.

  

        Transfer oiltank with pneumatic rollers         Transfer caissoon onto submersible barge

Facilities of airbag heavy lifting and transfer

Similiar to ship launching and docking facilities, the main equipments include winches, airbags and air compressors.

 

               Winches for caisson moving/transfer              Marine airbags for caisson transfer

Lift and move Caissons with airbags 

Caisson lift with airbags

To apply airbag lifting technique people need to reserve rooms for placing deflated airbags when fabricate caissons. Generally there are two ways to do it. 

Trough Method

Trough method is labor saving and suits for fabricating caissons in scale.Those concrete troughs measured by 1.5-2.0 meters wide and 30-40 cm deep that can hold one deflated airbag. Once caisson is ready to move,  marine airbags will be placed into the troughs and pumped to lift caissons up. There will be a relay lifting to enable airbag can roll on the flat ground, when caisson is lifted up 30 cm high from ground, relay airbags will be inserted. Those relay airbags on ground will take over caisson and troughs will be coverd with cap, then the caisson is ready for transfer.

 

         Concrete channels built on caisson fabrication site   Insert airbags into trough for caisson lift 

Beam/block Method

Block method is simple compare with trough method and suits for temporary caisson building and transportation. The blocks can be concrete beams or H type girders whose height should be 30-50 centimeters. The space of blocks is decided by airbags' diameters, generally should be not less than 2 meters and stuffed with wet sands during caisson fabrication period.

When caisson is ready, stuffed sands between beams will be flushed out by high pressure water to make rooms for lifting airbags. When caisson is lifted from beams by airbags, beams will be removed. 

 

                    Fabricate caisson on concrete beams    Insert airbags between support beams

Reference project: LPG Tank Lifting with airbags

Transfer Caisson with Airbags

Generally caissons will be fabricated in more than one rows, some caissons will need to be moved transversely to the transport passage first. Still there will be a relay lifting, once caisson is moved to the passage, solid blocks will be placed to support caisson. Then airbags will be deflated, removed, then placed again with a 90 degree direction turn.

 

Winches are employed in the caisson transport project, one is to offer pulling forward force, another is designed to hold the caisson. The two winches will be operated in coordinated manner, one pulls another releases, one stops another stops also. Considering the move stability the working heights of airbags is generally between 40-50 centimeters. 

To float caissons, people usually move caissons aboard semi-submersible barge or floating dry dock for launching. See airbag caisson transport calculation to know the operation details. 

 

              Use winches from floating dock as the pulling force       Restraint winch on the shore

Reference project: Caisson transfer with airbags in Tieshan port

Launch Caisson directly with Airbags

Caissons may be directly launched into water with marine airbags if there are suitable conditions, usually high tide difference will be essential. People will move caisson to the sea in low tide then wait for high tide to float caissons. Marine airbags are often used as floating assistant to float caisson in high tide time.

Also with good designed launch ramp and water condition, concrete blocks can be launch with airbags like the steel vessels. The bending moment should be strictly limited during the launch to prevent any possible damage of blocks.

  

Reference project: Launches 1400 T pumphouse with airbags

Working efficiency of airbag caisson transfer

The caisson moving speed of airbag transfer system is about one meter per minute. Comparing with trolley transfer , airbag heavy move is slow. One eight people group can transfer or launch three caissons in two days that can satisfy most demands of the project.