A Beautiful Pearl Necklace on the Indian Ocean—Documentary of China-Maldives Friendship Bridge

On July 9, 2018, in the beautiful island country of the Maldives, the builders of the China-Maldives Friendship Bridge successfully completed the final closure of its steel box girders. On the water area between the Male Island and Hulhule Island, three V-shaped piers of the bridge, like three soaring seagulls, connect the two islands.

The challenges and difficulties conquered by the Chinese construction team have successfully demonstrated China's prowess in bridge construction.

The China-Maldives Friendship Bridge is 2000 meters in total length, of which the main bridge covers 760 meters. It is also a six-span (180 meters/span) composite rigid frame bridge, so the most important part of the composition was the hoisting of steel box girders.With a maximum water depth at the construction site of nearly 50 meters, and a wave height reaching up to 5 meters, the sea conditions were extremely poor,the amplitude of a heavy-lift ship could reach up to 1 meter, and its swing amplitude could reach up to 2 meters. It's a challenge for both personnel and equipment to hoist the steel girders to a designated position, increasing the risk of a crash against the bridge deck.

Engineers designed in advance a soft-landing cushioning device: a soft sponge pad which served to secure a soft landing of the steel girders, and increased the security level. During the landing of the steel girders, instructors at the forefront of the construction site would keep a close eye on the patterns of sea waves, and gave instructions when waves started waning. The operator would make response upon the delivery of such instructions and completed a perfect “soft landing” for every section of the steel box girders.

The main bridge of China-Maldives Friendship Bridge has a free height of over 60 meters from the seabed to the top of the deck, and the length of the cantilever of the concrete beam on the upper part of the V-shape pier is 65 meters. Its whole structure resembles a seesaw standing in the sea. Conducting the closure of large sections of steel box girders weighing as much as 600 tons and keeping the balance are also challenges faced by the engineers.“If the balance is broken, the main bridge, if not suffering from disruptive damage, will at least have its beams and piers cracked,” warned Li Ning, deputy chief engineer of the project. Through strict analysis,simulative calculations, and construction control,engineers made 26 individual weight adjustments in the 95-meter-long incremental launching process.That meant making a weight adjustment at an average of every 3.5 meters, with a total adjusted weight of more than 1,000 tons.

Monitoring data indicates that the swing amplitude of the cantilever of the main bridge could reach up to 3 centimeters, and under the effect of large temperature differences, the length difference of the joints of the closure could vary 2 centimeters.How to ensure the precision of the bridge's closure under such conditions was a big problem faced by the bridge builders. The construction team employed the method of lowering the large sections of steel box girder and cut them multiple times to meet the precision requirement of the closure. It took 900 days for the Chinese and Maldivian engineers to succeed.

Ibrahim, a 70-year-old local man, commented excitedly, “It is an extremely exhausting journey to Hulhule Island or Male Island by boat if you encounter bad sea conditions. From now on, we can go to the airport by car. The bridge will bring convenience from generation to generation.”

中马友谊大桥全景俯瞰A Panorama of the China-Maldives Friendship Bridge

串起印度洋上的美丽“珍珠”——援马尔代夫中马友谊大桥纪实

2018年7月9日，在风光旖旎的马尔代夫，一座由中国中交二航局承建的大型桥梁工程——援马尔代夫中马友谊大桥，成功合龙。在首都马累岛与机场岛之间的海面上，这座大桥的三个V型墩像三只海鸥，展翅飞翔，将两座岛紧紧地联结在一起。

中国团队这次建桥过程中经历的挑战，有力地证明了中国建桥力量的实力。

中马友谊大桥全长2000米，主桥长760米，为六跨180米叠合钢构桥，所以钢梁合龙是重要环节。在最大水深50米、涌浪最大高度5米、船舶上下升沉幅度1米、左右摆幅超过2米的情况下，如何把钢箱梁吊装到位，是对技术和装备的严峻挑战。一不小心，极可能造成钢梁与桥面碰撞受损。

2018年6月24日，援马尔代夫中马友谊大桥主桥20号墩至21号墩之间的钢箱梁正在顶推。Installation of steel box girders between Pier 20 and Pier 21 of the main bridge of the China-Maldives Friendship Bridge on June 24, 2018

2018年6月29日，援马尔代夫中马友谊大桥最后一个钢箱梁合龙段施工准备工作。On June 29, 2018, engineers preparing to conduct the final closure of steel box girders for the China-Maldives Friendship Bridge

工程师们提前设计出一套钢梁着陆缓冲装置，让钢箱梁下落后就像落在一个柔软的海绵垫上，有效增强了安全性。在钢梁下落过程中，一线起重指挥人员不断把握海浪起伏规律，实现了每节钢箱梁的完美软“着陆”。

中马友谊大桥主桥墩净高超过60米，左右混凝土梁悬臂各长65米，看起来就像海中的跷跷板。如何实现重达600吨的大节段钢箱梁从桥面上顶推合龙，掌握好桥两端承重平衡，这又是一大挑战。“若桥体失衡，轻则造成梁体和墩身开裂，重则导致主桥倾覆性破坏。” 项目常务副总工李宁指出。在钢梁95米的顶推行程中，累计进行了26次配重调整。钢梁平均每前进3.5米，就进行一次配重调整，累计调整重量达1000余吨。

监测发现，主桥悬臂梁体在强涌浪中的晃动幅度达到3厘米；再加上昼夜温差变化，合龙口的长度变化接近2厘米。在这样的情况下，要保证大桥的合龙精度，要将配切后的焊缝宽度控制在1厘米以内，误差不超过5毫米，又是一大挑战。建设团队采用“大节段钢梁横向错位下放、分次配切就位合龙”的新方法，实现了毫米级误差合龙。中马建设者奋战900多天，终于迎来这一重大胜利。

年近70的易卜拉欣老人激动地说：“如果海况不好，坐船到机场岛或胡鲁马累岛实在太难了。今后，可以打车过桥直达对岸，世世代代都方便了。”