On April 1, 2014, the "Sewol" passenger ship carrying 476 people set off from Incheon Port in northwest South Korea and headed to Jeju Island in the southwest. Water sank in the southwest waters, resulting in the death of 304 people, most of which were high school teachers and students participating in the study tour.
There are many speculations about the sinking of " Segoyle ", including sudden steering, modification, overloading, explosion, rocket hit and conspiracy theories. There is no official conclusion yet on why the ship sank.
In April 2015, on the first anniversary of the shipwreck of the Sewon ship, the South Korean government, under pressure from domestic public opinion, decided to salvage the Sewon to find out the cause of the accident and find 9 missing persons.
Sewol weighs about 6824 tons, and the weight in water exceeds 10,000 tons. It is not easy to salvage the water as a whole. The requirements put forward by South Korea are very strict. The shipwreck must maintain its original state with a left tilt of 90 degrees, and the hull structure must be kept intact.
0,000 tons of hull is soaked in the deep sea and is in an inclined posture. Bound with steel ropes, what should I do if the ropes are tied into the hull and cause secondary damage to the victims? What should I do if the hull is broken?
The powerless South Korea finally had to choose international bidding, with a total of 19 countries participating, combined with technical scores and price scores, finally took over. There are two key points in salvage: one is how to ensure that the hull is completely out of water, and the other is how to continue to maintain an underwater posture after it is out of water. The Shanghai Salvage Bureau has adopted a plan to support steel beams and hydraulic lifting. The key to supporting the bottom of the steel beam is to support it and hold it firmly. The key to improving the hydraulic is to keep pace and obey orders on high winds and heavy waves.
Therefore, the overall floating of the "Sewol" shipwreck is completed by the barge floating method, including four operational links: lifting and lifting out of water, dragging and displacement, moving semi-submersible and overall floating out of water. It is necessary to connect the 33 steel beams placed at the bottom of the "Sewol" shipwreck with the lifting steel strands arranged on the two large lifting barges. Then, through a hydraulic lifting device, the "Sewol" sinking 45 meters underwater is lifted to the designed height of 13 meters in the outlet, and dragged the whole of the tugboat to the pre-sinking semi-submersible barge. Finally, the wreck was lifted out of the water by a semi-submersible.
However, the data given by the Koreans are extremely unreliable. The actual weight of the Sewol is larger than that given by the Korean side, and its center of gravity is not accurate. This makes it even more difficult to move the Sewol to semi-submarine and to carry it to an ideal docking height.
get! In a word, the data given by Koreans are inaccurate. In the end, we have to clean up the mess. This is also the reason why we lost 1.1 billion in the end.
Because the data is inaccurate, it is necessary to conduct underwater three-dimensional precision scanning of the shipwreck, and to conduct marine environment, water, meteorology, landforms, geology and other adjustments in the shipwreck sea area.
China spent 590 days to find out the hydrology and sea conditions of the shipwrecked waters. During the 590-day operation, the Shanghai Salvation Bureau invested more than 3,000 ships and 2,170 construction workers. Among them, the diving operations that account for a large proportion of operations have completed more than 6,000 diving operations, and the total underwater operation time is nearly 13,000 hours. The long project time and arduous tasks have created the world's largest.
During this process, we also found that there was a large reef area in the bottom of the shipwreck, which was significantly different from the information provided by the South Korean side, resulting in the installation of 10 steel beams at the stern of the ship being extended for 4 months and the steel beams were difficult to penetrate. We adopted the method of airbags entering the ship and draining the hull with auxiliary lifting and lifting the hull. We used 33 steel beams to pass through the rocks under the sea and installed them at the bottom of the ship. The overall lifting of the water finally laid the foundation.
After the salvage operation begins, it is necessary to conduct water navigation and positioning and communication cooperation management of each construction ship, conduct water underwater navigation and positioning of submersibles, provide underwater positioning services for underwater steel beam operation, sealing operation, and oil pumping operation, conduct underwater positioning and underwater three-dimensional attitude monitoring of shipwrecks, as well as moves to the semi-submersible ship after salvaging out of the water, and navigation positioning during the floating to the dock, especially real-time attitude monitoring during the overall floating and lifting process, is the key to the project. The bad conditions in the shipwreck waters are harsh, and there are many ships participating in the construction and many diving operations.
, and China innovatively used multi-beam and three-dimensional scanning sonar to conduct attitude detection on the shipwreck, obtain the three-dimensional point cloud data and detailed structural characteristics of the shipwreck, and complete the model reconstruction of the underwater state of the shipwreck; monitor current in real time and integrate the data into the navigation and positioning software to guide the diving construction work; build a local area network at the construction site to realize the display of multiple ships, multiple sensors, and multiple terminals; by sharing beacon , the operation mode of multi-ship USBL collaborative positioning is realized, ensuring high-precision installation of steel beams; monitor the attitude of the shipwreck during the overall floating process, and realize the three-dimensional visual display of the shipwreck based on BIM technology.
In addition, this salvage work is also the first show of Zhenhua 30. For this salvage work, the Shanghai Salvage Bureau and Zhenhua Heavy Industry customized Zhenhua No. 30 . Zhenhua 30 ranks first in the world with its single-arm lifting capacity of 12,000 tons and 7,000 tons of 360 degrees full rotation lifting capacity. During the lifting weight test, the ship successfully lifted ships above the maximum lifting weight capacity 110%.
The joint salvage operation of the "Sewol" was officially launched on March 22, 2017. By March 28, the "Sewol" was released from water. This process took only six days, which is closely related to the long-term and meticulous preparations of the Shanghai Salvation Bureau in the early stage. , and the difficulty and risk of salvaging a 6825-ton wreck from a water depth of 44 meters is unprecedented.
It can be said that although we lost money this time, we have comprehensively used a number of innovative technologies in the salvage process. has accumulated experience and technical reserves, and has enhanced our voice in the global market. This cannot be measured by money. And the advertising benefits cannot be measured.
