Thursday, December 15, 2011
Eversafe project of concrete structure shift with air bags
Tieshan Port Industrial Park is located in Guangxi Zhuang Autonomous Region, China. The Park is one of the three important industrial zones for the Beibu Gulf Development, which was approved by China’s Central Government.
The construction project consisted of two phases: the NO.1-2 berth construction have already been finished and NO.3-4 berths construction work started from August 2010.
In plan total 40 Caissons will be installed for NO.3-4 berths construction. Eversafe Marine was engaged by the Administration for the Beibu Gulf to carry out caisson transportation works, from fabrication site to submersible barge with heavy lifting marine airbags. Caisson transportation with marine air bags is a new technology which doesn’t need rails and trolleys and can transport concrete structure on compacted ground. So it enables fabricating caissons on temporary site which can be located near shipping position. Using balloons to transport caissons to submersible barge then launch it can save more than 40 percent investment comparing with trolley transportation method,not mention the time saving.
The first caisson measures 24 meters by length, 16.4 meters by width and 20.75 meters by height. Its weight reaches 3050 tons. To move caissons from construction site to shipping out position , Eversafe team made the masterly plan which consists of three steps: lifting first ,length ways move then transverse move. Total four winches were employed to control caisson movement: two winches from submersible barge to pull caisson move forward and other two winches were used to stop caisson.
Total 8 pieces heavy lifting air bags with 1 m diameter and 16 meters length were used to lift the caisson. Each air bag carry about 380 tons with 0.25 Mpa pressure. To roll caisson out 24 pieces 8 meters long air bags were arranged in two rows and kept in 40 cm height to ensure caisson movement stability. It took us about 3 hours to transport the first caisson to ship out position.
When using air bags to move caissons aboard submersible barge, the barge need not to sit on seabed. Often people use steel plates to connect bank and barge deck to roll caisson on to board. Submersible barge can rise or sink by adjusting ballast water to adopt coming caisson. And in flood tide the barge operation will be easier.