After the disastrous accident that has happened on 11th September 2015 that killed 109 people, Dutch heavy lifting specialist, Mammoet, has been called in in the recovery and designing of the lift plan.
The 1,350 tonne Liebherr LR11350 has been configured with full 84 metres luffing jib as well as full 102 metres main boom while carrying out construction work inside the mosque. While the crane was not able to withstand the high wind load that day, it has tilted into the building.
Removal of the Collapsed Crane’s Boom
|Portion of the cut jib sections.|
Image from the construction index.
One of the main challenges was the removal of the jib sections that had penetrated through the roof and entered two levels of the buildings.
Consultant Dar has helped the contractors to design a shoring system to transfer the load into the column and beams in order to reduce the weight on the roof.
At the same time, Mammoet has designed a 6 metres high wall supported with concrete blocks to prevent the crawler crane’s body from sliding into a main water supply.
With the assistance of two tower cranes, HC-L 335, 55 ton and 540 HC-L, 60 ton, the 20 ton jib sections are lifted while the sections are being cut as the pins of the boom and jib were twisted and cannot be removed.
The other challenge was the removal of the 100 ton main boom sections while preventing further damages to the Massa facade. Five cranes, consist of LTM1500, AC700, two LTM1400 and LTM1225 was being used. While the first four cranes are being used to lift the boom sections, the LTM1225 was used to hold the winch drum and its components. The site’s HC-L 335 tower crane was used to release the boom from the facade wall.
Race Against Time
The biggest challenge was the time constraint. Both the contractor and government were working continuously for 24 hours to remove the wreckage of the crane safely and to open the roof and Massa before the peak pilgrimage season from 22 September to 28 September.
More details of the story can be found at The Construction Index.