Recently, the 2021 National Bridge Academic Conference was held. Academicians of the Chinese Academy of Engineering Zhang Xigang, Zhou Xuhong, Nie Jianguo, Li Shucai, Liu Jiaping and other top experts in the bridge industry gathered in Quancheng to showcase bridge projects with more than 500 authoritative talents from all over the country Construction achievements, mutual learning of bridge engineering construction experience.

The participating experts came to the construction site of the Zhanlin Yellow River Bridge, which was built by the CCCC First Public Corporation Group, to observe and experience the implementation and application of assembly construction technology and bridge intelligent construction technology.

The conference was co-organized by the CCCC First Public Bureau Group. The Zhanlin Yellow River Bridge built by the company once again became the focus of the audience. Not only did they exchange technical achievements at the conference, but also welcomed the experts attending the conference to observe on-site.

The chief engineer of the project shared the "Complete Construction Technology of Prefabricated Bridge Deck of UHPC Steel-Concrete Girder Without Coarse Aggregate" summarized by Zhanlin Yellow River Bridge

What is so special about being on the Yellow River Bridge? Let's find out! In China, known as the "infrastructure maniac", bridge construction has been evolving and never stopped.

A new bridge on the Yellow River in Shandong Island - Zhanlin Yellow River Bridge is under construction. As the bridge with the largest span in the lower reaches of the Yellow River, it will complete a new span here - the first full-section push of domestic bridge construction.

Zhanlin Yellow River Bridge Full Section Pushing Construction

Extremely lightweight structural design

The Yellow River Bridge on the Zhanlin Expressway (referred to as "Zhanlin Yellow River Bridge") is a key control project on the whole line. The main bridge is a 962-meter-long, double-tower composite beam cable-stayed bridge. Its main span (crossing the Yellow River part) is 442 meters. meters, which is currently the longest span in the lower reaches of the Yellow River.

Zhanlin Yellow River Bridge renderings

The bridge site is located at the junction of Binzhou and Dongying in the lower reaches of the Yellow River. Due to the special geographical environment, the lower reaches of the Yellow River are not navigable, and the main span beams cannot be transported and hoisted by water like general bridges across the river.

Sediment deposited has caused the lower Yellow River to become an "overground river", which is not navigable

Therefore, the Zhanlin Yellow River Bridge adopts the jacking method for the erection of the main span beam, which is different from the past, this time it is a "full-section" jacking.

Compared with the traditional jacking, the full-section jacking can realize the integrated jacking with the bridge deck cover, which takes less time, but requires higher material performance and manufacturing process of the bridge deck cover. The key is the "UHPC bridge deck cover".

Why UHPC?

Compared with traditional reinforced concrete, the mechanical properties of UHPC with proper reinforcement are close to that of steel structure, which not only avoids the danger of cover plate breaking when the full section is pushed up, but also makes the span of 962 meters long with ultra-thin and ultra-high performance. It can realize one push and direct molding.

Adjacent to the storage area for the UHPC deck cover of the Yellow River Bridge. The thickness of the UHPC bridge deck cover is only 17 cm, which is about 1/3 of the thickness of the traditional concrete cover, but the mechanical performance is increased by 3 times, which reduces the weight of the whole bridge by 30%

In addition, unlike the traditional non-full-section jacking first and then the cover, the full-section jacking construction period is shortened by half a year.

Such an extremely lightweight structural design makes the bridge jacking construction lighter, stronger and faster from now on. It is highly in line with the green and low-carbon concept, representing and leading the future development direction of long-span bridge construction, creating a new type of similar project. construction technology.

Why use it now?

In fact, the material of UHPC has been disseminated in China as early as 1998 by Professor Qin Weizu of Tsinghua University. However, it is an innovative practice to integrate UHPC with the bridge deck cover and directly carry out the jacking construction. And this, can't beat a wise player.

How do we do it?

NO.1 special production equipment

Tailor-made, UHPC paver all-in-one machine, transport skid trolley, realize mechanized substitution and automatic reduction of personnel.

NO.2 Tailor-made production line

It is divided into 4 major areas: material storage area, concrete mixing area, prefabrication area, high temperature steam curing area, and operations do not interfere with each other.

NO.3 High standard production process

Each step of quantitative, standard, and time-based production has been precisely controlled, and the fully enclosed intelligent CNC steam curing room enables the UHPC bridge deck cover to be maintained in the environment of "20℃ standard curing + 90±1℃ high temperature steam curing". It reaches the material performance limit healthily and steadily, and the strength and shrinkage are both completed by more than 95%, which can be used directly on the bridge.

10,000-ton super long-distance push

Next is the installation of the finished product. How to make each section of the 410-ton behemoth smoothly hoist into place?

The project team adopted the method of "breaking the whole into pieces", transporting and hoisting the panels and steel components of the composite beam according to "modules", and forming "building blocks" at the bridge head position, which greatly reduced safety risks and construction costs.

In order to make the jacking construction process more coordinated and efficient, they found inspiration in the "assembly line production workshop". The operation platform is divided into three major areas of water circulation operations: beam section assembly (building block forming), wet joint pouring and maintenance (building block bonding), and beam section jacking, so that the operation time of each jacking round is reduced from 30 days to 15 days.

The dripping display of advanced means of modern bridges

The "extremely lightweight" structural design and the application of high-strength materials make the full-section jacking of steel-concrete composite beams a reality, but the construction difficulty of 962 meters and 27,000 tons is still at the forefront of the industry, ensuring line accuracy and avoiding steel structures. Deformation and panel cracking are always a top priority for construction control.

Full-section jacking construction with bridge deck

If such a huge amount of engineering is compared to a battle, the construction monitoring center is undoubtedly the headquarters of this battle. Modern bridge construction automation, digitization, and intelligent advanced technological means are vividly reflected here.

The intelligent walking jacking system is the power source for the movement of the beam body. Through remote automatic control, nearly a hundred sets of jack equipment can be uniformly stressed, so that the 10,000-ton composite beam can move forward smoothly according to the preset working conditions.

The remote wireless stress monitoring system and the Beidou satellite positioning system are the "health detectors" of the composite beam during the jacking process, through real-time monitoring and early warning, automatic data analysis and other functions, to ensure the healthy "walking" of the composite beam at every step.

The remote wireless video surveillance call system is the "Sky Eye" of construction management. It conducts all-weather "tracking" of the on-site environmental conditions and construction status without dead ends. With the remote call function, the construction process can be communicated with all-round visual and barrier-free.

Adhering to science and technology as the forerunner, the builders of CCCC No. 1 Public Bureau Group adopt the ultimate craftsmanship of lightness and toughness, constantly temper the ultra-high craftsmanship of the millimeter level, and explore new innovations by driving the mighty steel dragon on the Yellow River! Looking forward to the successful practice of full-section jacking of steel-concrete composite beams, which will bring a new leap to China Bridge in the near future! Editor/He Yuting