On both sides of Dongting Lake, a “giant dragon” proudly spans; two “rainbows” reflect on the shimmering waves. This “giant dragon” and these “rainbows” form an important section of the national Hangrui Expressway in Hunan—the Hangrui Dongting Bridge.
　　The bridge has a total length of 2,390 meters and a main span of 1,480 meters. Its main span ranks first in China and second in the world among steel truss stiffening girder suspension bridges, and it is known as a “super project” in world bridge construction.
On January 27, 2018, a team of experts and scholars from the Ministry of Transport, renowned universities and design institutes both within and outside the province, construction units, and transportation departments gathered in Yueyang, Hunan. After on-site inspection and verification of the Hangrui Dongting Bridge, which is scheduled to open to traffic soon, the expert panel highly praised its construction management, design, and construction innovations.
　　Challenging the Natural Moat, Pioneering with Courage
　　The 800-li Dongting Lake, known as the “Land of Fish and Rice” and the “Kidney of the Yangtze River,” stretches vast and boundless.
　　Since ancient times, Dongting Lake has been an insurmountable “chasm” separating people on both shores. In Yueyang, a Dongting Lake Bridge was completed and opened to traffic in 2000. With the growing development of transportation, a single bridge can no longer meet the needs of local economic and social development.
　　In October 2013, construction of the Hangrui Dongting Bridge officially began. This bridge is the easternmost section of the Hangrui National Expressway in Hunan—a key control project of the Dayue Expressway.
　　However, as early as four years prior, the bridge construction team had already entered the site.
　　“From feasibility study to preliminary design, and then to completing relevant tests, it took four years in total,” said Chen Guoping, manager of the Dayue Expressway Dongting Lake Bridge Construction and Development Co., Ltd., with emotion. The Hangrui Dongting Bridge is located at the confluence of Dongting Lake and the Yangtze River, crossing three types of terrain: the Yueyang riverside levee, the Xiangjiang navigation channel, and the Junshan shoals, making construction extremely difficult.
　　First, the main bridge of the Dongting Lake Bridge is located at Chenglingji Port, where more than 700 vessels pass through daily. The ships are large-tonnage and fast, posing significant safety risks.
　　Second, the Dongting Lake area has a changeable monsoon climate with frequent fog, strong winds, and heavy rain. The water level is affected by the hydrology of Dongting Lake and the Yangtze River, and the flood season with water levels exceeding the design construction level lasts for a long time.
　　Third, the anchorage on the Junshan side is located on the beach of Dongting Lake, where the silt layer is thick. Excavation of the anchorage foundation pit is difficult and prone to safety risks such as water and mud inrush.
　　Facing these natural adversaries to bridge design and construction, the builders rose to the challenge. Based on geological and hydrological conditions and through research and comparison of technologies, techniques, and materials, they completed the construction of this extra-large suspension bridge safely and with high quality.
　　The design inspiration for the bridge comes from the Yueyang Tower and the pan flute. The two towers are designed as classical towers with the theme of “Xiaoxiang Melody.” The cable towers are tapered overall with a stepped shape and elegant appearance.
　　The two cable towers are 206 meters and 203 meters tall respectively; the bridge has a total length of 2,390 meters and is designed with six lanes in both directions. The main span is 1,480 meters, which is 304 meters longer than the Aizhai Bridge, which set four “world firsts.”
　　“This is another world-class extra-large suspension bridge!” commented Chen Zhengqing, academician of the Chinese Academy of Engineering and professor at Hunan University.
　　Technology Leading, Eight Innovations
　　Facing the natural moat, only courage to innovate and strive for excellence can break through the difficulties! During the construction of the Hangrui Dongting Bridge, the builders carried out scientific and technological research and independent innovation, overcame a series of difficulties, proposed effective construction technologies and management plans, and applied various new technologies and processes.
　　The bridge achieved eight major innovations, and its innovative achievements and construction management experience can be promoted and applied in future bridge construction.
　　First, it is the first time that a plate-truss composite ultra-high performance concrete lightweight composite deck structure has been used on a highway suspension bridge. Previously, most steel bridges in the world used orthotropic steel plate decks with asphalt concrete pavement, which are prone to rutting, potholes, cracks, and fatigue cracks in the deck system. Facing this challenge, the builders of the Hangrui Dongting Bridge took a novel approach and developed a new lightweight composite deck structure made of ultra-high performance concrete. Simply put, a layer of ultra-high performance concrete is paved on the steel bridge deck, followed by a wearing layer. The successful application of this technology is of revolutionary significance to steel bridge deck pavement technology worldwide, and China will usher in a climax in the use of high-performance concrete lightweight composite structures.
　　This composite structure can save 12% of the steel used in the main girder, greatly reducing the scale and cost of foundation engineering. At the same time, it can reduce the fatigue stress on the steel plate caused by wheel loads by about 80%.
　　Second, a new type of flexible wrapping tape protection system for the main cable was pioneered in China. Due to the special environment, the main cable is not only eroded by water vapor from the lake area but may also be corroded by gases from nearby chemical plants. Anti-corrosion became another challenge in main cable erection.
The builders ingeniously sealed and wrapped the main cable with a tape and used dehumidification equipment to discharge moist air and keep the interior of the main cable dry. This new flexible wrapping tape protection system for the main cable was used for the first time in a super-large bridge in China.
　　Third, it is the first time that environmentally friendly treatment technology for bridge construction wastewater has been adopted. The bridge crosses the Dongting Lake ecological protection zone. To minimize pollution, the builders conducted research on key technologies for environmentally friendly treatment of bridge construction wastewater, enabling the treated wastewater, after sedimentation and biological purification, to reach a quality nearly suitable for direct reuse. This invention won the second prize of the Science and Technology Award of the China Highway Society in 2016.
　　Fourth, the multi-girder rigid connection window closure technology was applied for the first time. Girder hoisting and installation is an important part of bridge construction. To complete the construction schedule as planned, the builders optimized the girder connection plan and adopted a construction process of welding while hoisting, ensuring both construction progress and quality and safety. With the multi-girder rigid connection window closure technology, up to five girder segments could be erected and installed in a single day.
　　On August 15, 2017, with the hoisting of the last steel truss girder segment into place, the deck of the Hangrui Dongting Bridge was successfully closed, one month ahead of schedule.
　　Fifth, 1,860 MPa high-strength galvanized aluminum alloy steel wires were used for the first time. The main cable of a steel truss suspension bridge is composed of many small steel wires. Previously, the maximum tensile strength of main cables in China's suspension bridges had gone from 1,000 MPa to 1,680 MPa. But for a long time afterward, no breakthrough was made in main cable tensile strength.
　　In the construction of the Hangrui Dongting Bridge, technical personnel developed and adopted 1,860 MPa zinc-aluminum coated high-strength steel wire main cable strands, achieving a new breakthrough in the strength and durability of high-strength steel wires for main cables.
　　Sixth, a new gourd-shaped underground diaphragm wall structure was pioneered. Conventional anchorages are two semicircles of equal size, but the Hangrui Dongting Bridge adopted a “gourd-shaped” design with a small circle radius of 28 meters and a large circle radius of 32 meters. This design reduces the engineering quantity of the anchorage foundation while ensuring that the forces meet code requirements, saving project cost. In short, it adapts the most economical foundation engineering to the structural requirements of the anchorage.
　　Seventh, new large-diameter drill bits were invented. During construction, the team independently developed six types of drill bits, including a pure rolling spherical-tooth conical-bottom drill bit and a spherical-tooth conical-bottom double-suction-port drill bit for large-diameter pile drilling in bridge foundations. Drilling efficiency nearly doubled, and six utility model patents and one invention patent were obtained.
　　Eighth, a large-tonnage eddy current axial damper was applied for the first time. After installation of this damper on the entire bridge, the durability of auxiliary structures such as expansion joints and bearings can be greatly improved, and their wear can be slowed, thereby extending the service life of the bridge.
　　These technical specifications and research innovations represent a new height in bridge construction and demonstrate the new achievements of Hunan expressway people in implementing the province's “innovation-driven” development strategy.
　　A Century Project, a Magnificent Wonder
　　The Dongting Lake Bridge construction task is heavy, the responsibility great, and the time tight. Under complex and arduous conditions, ensuring quality requires a sound management system, iron-fisted supervision measures, and vigorous execution.
　　In March 2017, when Chen Guoping took office as project manager of the Dayue Expressway Dongting Lake Bridge Company, he faced an unfavorable situation of lagging progress. He realized that it was necessary to fully mobilize everyone's initiative and go all out to achieve the goal and build a true century-quality project.
　　After the new company leadership team was formed, they immediately carried out problem-oriented investigations, performance supervision, and rectification implementation, creating a good atmosphere where everyone wants to do things, everyone can do things, and everyone can accomplish things.
　　In view of the great difficulty, new techniques, and complex geological structure of the bridge construction, the command center organized multiple expert review meetings for technical disclosure; formulated strict construction plans, processes, and technical documents to ensure smooth construction step by step.
　　Quality is the life and starting point of engineering construction. To build a “world-class bridge” and a “new名片 of Hunan,” the builders of the Hangrui Dongting Bridge have never relaxed their vigilance on quality and safety.
　　Scenes of bridge construction remain vivid, and the figures of bridge builders appear before our eyes—
　　The first concrete pouring of the upper crossbeam of the bridge cable tower was a very critical construction node and a highly risky construction procedure. Zhu Lishan, project manager of Section A1 of the Dongting Lake Bridge Project of Hunan Road & Bridge Construction Group, who was responsible for this section, was suffering from severe gout at the time, and every step felt like a knife cutting his foot. But he still went to the front line despite his illness and led the technical personnel through more than 40 hours without sleep to successfully complete the construction task. Colleagues sincerely exclaimed that Zhu Lishan was truly an “iron man of road and bridge.”
　　In October 2014, the bridge construction encountered a “bottleneck”: after the two-month flood season of Dongting Lake, some mud inclusions appeared in parts of the cable tower pile cap. No one had encountered this sudden situation before, and everyone was at a loss for a moment. Jiang Delin, executive deputy manager of Section A2 of the Dongting Lake Bridge Project of CCCC Road & Bridge, after a detailed understanding and survey of the situation, led everyone in the conference room to “fight” for more than ten hours, checking records, deducing procedures, and verifying data... and finally found the cause and determined the solution. Without time for a good rest, Jiang Delin stayed at the construction site and worked three days and nights without sleep to finally solve the problem.
　　It is precisely because of such engineering leaders and builders—“supporting the sky with a single pillar, writing the annals of history with towering bamboo shoots”—that no safety or quality accidents have occurred since the construction of the Hangrui Dongting Bridge began. The project has achieved fruitful results in construction progress, safe and civilized construction, and standardized construction, and has been widely praised.
　　The Hangrui Dongting Bridge project has successively won the Hunan Provincial People's Government's “2015 Hunan Provincial Key Construction Project Target Management” Excellence Award, the Hunan Provincial People's Government's “2016 Hunan Provincial Key Construction Project Target Management” Outstanding Unit, the 2016 “Hunan Expressway Craftsman” Best Project Company, and has repeatedly won the first prize in the Hunan Provincial Expressway “Bridge Construction Standardization” Labor Competition and the title of Advanced Unit in Hunan Provincial Expressway Construction Project Target Management.
　　The suspension cables stretch across the sky, the long bridge hangs against the sun, and the natural moat has become a thoroughfare. The breathtaking Hangrui Dongting Bridge carries the profound history of the Baling land, embodies world-leading science and technology and the pioneering Hunan spirit, and is the pride and glory of Hunan's bridge builders and expressway people!