Looking eastward from Lovers Road, the most beautiful coastal avenue in Zhuhai, the 55-kilometer-long Hong Kong-Zhuhai-Macao Bridge is like a dragon winding on the blue sea. This is the longest sea-crossing bridge project in the world, and it is also the most difficult and challenging super project in comprehensive construction: building a giant steel bridge with a service life of 1.20 years in stormy seas, building the longest immersed tunnel at a depth of more than 40 meters under the sea, crossing the construction site of a 300,000-ton waterway and a white dolphin reserve ... It can be said that every challenge is unprecedented.
"The Hong Kong-Zhuhai-Macao Bridge is a veritable bridge of science and technology. Behind these world-class challenges are a series of powerful drivers of innovation and technological support. " Su Quanke, chief engineer of the Hong Kong-Zhuhai-Macao Bridge Administration, said that since the preparatory work began in early 2003, more than 200 scientific research units and thousands of scientific and technological workers have carried out more than 300 scientific research projects around the construction of the Hong Kong-Zhuhai-Macao Bridge, and finally this world-class project has been held up.
At present, the main project of the Hong Kong-Zhuhai-Macao Bridge has been completed. I visited the "Mount Everest" in this bridge yard.
"After the bridge is opened to traffic, the journey between Zhuhai, Macao and Hong Kong will be shortened from three hours to half an hour. This bridge connects the Pearl River Delta region and forms a one-hour economic life circle of Hong Kong, Zhuhai and Macao! " Standing at the entrance of the Zhuhai section of the six-lane Hong Kong-Zhuhai-Macao Bridge, Su Quanke said.
"Several famous cross-sea passage projects in the world, such as the Chesapeake cross-sea project in the United States, are 19.7 kilometers long, with an artificial island area of 32,000 square meters and a submarine immersed tunnel of 3.3 kilometers; The Jochey Island-Busan Liandao Bridge in South Korea is 8.2 kilometers long, and there is no artificial island and 3.7 kilometers of submarine tunnel. Our cross-sea section of the Hong Kong-Zhuhai-Macao Bridge is 22.9 kilometers, and two artificial islands of 65,438+10,000 square meters will be built. The length of the cross-harbour tunnel is 5.9 kilometers, and the difficulty can be imagined. " Su Quanke introduced.
What's more, this construction is still in the open sea with deep silt and serious marine corrosion environment. The natural conditions are complex, and the requirements for ecological environment protection are more stringent. This sea area is a national first-class nature reserve to protect Chinese white dolphins. How to minimize the interference to white dolphins in the construction process is a severe challenge faced by construction workers.
According to the plan, the project will cross the 300,000-ton waterway and be adjacent to the Hong Kong International Airport. "This bridge must be built high to meet the needs of 300,000-ton ships, and it must also be built low to meet the height restrictions of flights landing at nearby airports." Su Quanke said that after comprehensive consideration, the most reasonable scheme of the Hong Kong-Zhuhai-Macao Bridge is the "bridge, island and tunnel traffic cluster project", that is, sinking into the seabed at this section, building a deep-buried immersed tunnel and building artificial islands on both sides of the tunnel.
"Artificial island construction and submarine immersed tunnel were all super problems for us at that time. Nanling dingyang is an open sea with many environmental sensitive points. It will take three years to build an artificial island if foreign technology is adopted. First, the construction period is too long, and second, it will have a serious impact on the marine environment. The key technology of submarine immersed tunnel has always been in the hands of a few developed countries, and the cost is very high whether it is technology introduction or cooperation. What's more, some technologies are still facing an international blockade, and money can't be bought. " Su Quanke said.
From the feasibility study stage of the previous project to the start of construction, the concept of scientific and technological innovation runs through. This super project has gathered thousands of scientific and technological workers in the fields of bridge design and construction, material research and development, engineering equipment and even ecological environmental protection, carried out more than 300 scientific research projects, obtained more than 100 invention patents, published more than 500 papers and created more than 40 construction methods.
The national science and technology support plan started the project of "Research and demonstration of key technologies for the construction of cross-sea cluster project of Hong Kong-Zhuhai-Macao Bridge" from 20 10, involving various difficulties in bridge construction. Professional, innovative and practical scientific and technological research has supported the construction of the Hong Kong-Zhuhai-Macao Bridge, gnawed hard bones, made comprehensive breakthroughs in key technologies, key equipment and key materials, and also played a leading role in the independent innovation and technological progress of China's transportation construction industry.
Overlooking the Hong Kong-Zhuhai-Macao Bridge from the air, the dragon suddenly disappeared more than 20 kilometers offshore and then vacated 6 kilometers away. The island connecting the two ends looks like an oyster shell, and the staff affectionately call it "Shell Island".
Shell Island is not simple. Two small islands with an area of 6.5438+10,000 square meters, from scratch in the open sea, started construction that year and became islands that year, setting a world record. "We have created a rapid island-building technology by deeply inserting super-large diameter steel cylinders into the high seas. It took only 22 1 day to build the two islands, shortening the construction period by more than two years and realizing green construction. " According to Su Quanke, the traditional technology of riprap and sea reclamation around dikes took as long as three years, which had a great impact on the surrounding environment and navigation channels. The researchers designed several schemes, and finally explored the rapid island-building technology in the open sea, that is, 120 giant steel cylinders were directly fixed on the seabed and inserted into the seabed, and then filled in the middle to form an artificial island. "Each cylinder is 22 meters in diameter, about the size of a basketball court; Up to 5 1 m, equivalent to 18 stories high; It weighs 550 tons, equivalent to an Airbus A380. "
The submarine immersed tube tunnel is also a giant. The immersed tube tunnel with a total length of 5.6 kilometers consists of 33 giant concrete pipe sections, each of which is180m long, 38m wide,1.4m high and weighs 80,000 tons.
"It is as difficult as the rendezvous and docking of spacecraft to make these pipe joints dock in the seabed soft foundation environment, which requires a series of technical support such as precise remote control, mapping and super-calculation." Xu, the person in charge of the research on the key technical topics of immersed tunnel design and construction, said that building a deep-buried immersed tunnel nearly 50 meters underwater is also regarded as a "technical forbidden zone" internationally. The island tunnel project of Hong Kong-Zhuhai-Macao Bridge is the first deep-buried immersed tunnel in the world. "The traditional immersed tunnel is shallow, but the load on the top of the immersed tube of the Hong Kong-Zhuhai-Macao Bridge is five times that of the traditional immersed tube. If the segmented pipe joint (flexible) is adopted according to foreign experience, there may be risks such as insufficient joint resistance and joint leakage. " Xu said that the technicians finally revealed the stress and deformation mechanism of the deep-buried immersed tube structure system in theory and innovatively proposed a new "semi-rigid" immersed tube structure. Compared with the scheme of "deep burying and shallow doing" proposed by foreign experts, this scheme saves the construction period.
"After the completion of the immersed tunnel, whether it will leak water is the key to success or failure. Because there are big joints between 33 pipe joints, each pipe joint has 7 small joints. The uneven settlement of foundation, the structure of shear key, the performance of water stop material and earthquake may all lead to tunnel leakage. " Xu said that in order to overcome these problems, they cooperated with many units to tackle key problems, and even it took more than two years to independently develop materials for making water stops. "The normal leakage rate of similar immersed pipe joints abroad is 5%- 10%. The semi-rigid structure improves the waterproof performance of the immersed tube structure, and the immersed tube tunnel of the Hong Kong-Zhuhai-Macao Bridge is watertight for the first time. "
As the largest steel structure bridge in the world, the steel plate consumption of the main girder of this bridge is as high as 420,000 tons. "This is equivalent to the weight of 10 Bird's Nest or 60 Eiffel Towers, and it can resist 16 typhoon and 7 earthquake." Su Quanke said that the paved area of the steel deck of the bridge reached 500,000 square meters, which also set a world record.
What's even more amazing is that this bridge is all made of "building blocks". All components of the Hong Kong-Zhuhai-Macao Bridge, regardless of their size, including piers, bridge bodies weighing thousands of tons and pylons with a height exceeding 100 meters, are manufactured in the onshore factory as a whole, and then transported to the sea, assembled together like building blocks, realizing precise manufacturing and installation.
"At the beginning of the design of the Hong Kong-Zhuhai-Macao Bridge, the concept of large-scale, factory, standardization and assembly was determined." Yu Lie, deputy director of the Hong Kong-Zhuhai-Macao Bridge Administration, said that the site is close to the waterway and there are more than 4,000 ships coming and going every day. In order to meet the needs of engineering quality, construction period and safety, and better protect the ecological environment, this brand-new bridge construction mode has been adopted. "Assembly at sea can reduce the interference of bad weather conditions at sea to construction and reduce the damage to the ecological environment. Shore prefabrication makes large complete sets of equipment and advanced production technology come in handy. "
Su Quanke said with emotion: "If the overall scientific research and equipment strength of the country has not reached this stage, it is unthinkable to make such an overall design."
The Hong Kong-Zhuhai-Macao Bridge needs to be a high-quality project, and its design life reaches 120 years, which is unprecedented in the history of bridges in China. "In the marine environment, fatigue cracking of steel bridge deck and early failure of concrete in marine erosion are common problems in the industry. To build a first-class project, we must rely on the power of scientific research to overcome these two ills. " As the person in charge of "Key Technology of Concrete Structure 120", one of the national science and technology support projects of the Hong Kong-Zhuhai-Macao Bridge, Wang Shengnian led the team to tackle key problems and made a durability design suitable for the Hong Kong-Zhuhai-Macao Bridge in terms of theory, technology, materials and technology.
The Hong Kong-Zhuhai-Macao Bridge is also a green project. At the beginning of the construction, the most worrying white dolphin was only1400; After the completion of the main project, the number of white dolphins increased to 1800. "This is also a sub-project of the National Science and Technology Support Plan. We cooperated with the Institute of Hydrobiology of Chinese Academy of Sciences, Sun Yat-sen University and the Planning and Research Institute of the Ministry of Transport to form a team, tracked more than 300 trips to the sea, took more than 300,000 photos, identified more than 1000 white dolphins in the sea area, and found out their living habits. Targeted protection measures were taken during construction. " Yu Lie said that seeing white dolphins at sea is a symbol of good luck. The workers are looking forward to meeting the white dolphins and deliberately avoiding them to make them less disturbed.