On the construction site of the Hengjing River Super-large Bridge on the Jianhu-Xinghua Expressway, a 100-ton-heavy prefabricated box girder is steadily settled on the prefabricated bent caps. After that, as the bridge building machine moves forward, a new round of erecting piers, setting up bent caps, and settling girders begins, forming an assembly line for bridge building.

 

It's the first time that the fully-prefabricated integrated assembled bridge building technique has been applied in Jiangsu Province. The Third Harbor Engineering-built 3rd section of the Jianhu-Xinghua Expressway has a total length of 9.2 kilometers, on which the 3,829.6-meter-long Hengjing River Super-large Bridge is a key project and its 9th to 23rd parts use   fully-prefabricated girders.

The construction site has bad geographic conditions of crisscrossing rivers, and branching streams, especially 20 fish ponds in the main line area of the bridge. If the project team applies traditional crawler cranes, all the fish ponds will be filled and that's a large-scale task with high construction risks and cost. To overcome the difficulty, the project team cooperated with the design company and the bridge building manufacturer to develop a piece of ungraded equipment. After 5 rounds of discussion, a new integrated bridge building machine emerged. This gigantic machine has a length of 80 meters, the 30-meter-long maximum span, and a 16-meter-high forward supporting leg.

Although to install fabricated parts is very convenient, this requires higher precision of the embedded parts. Another construction difficulty arose in how to make sure the correct assemble the hoisted pier with the supporting platform. The project team developed a pier overturning device and an embedded part locating model, realizing the overturning of the pier in the high air. As a result, the reserved sleeve at the bottom and the steel bars embedded at the top of the supporting platform were tightly matched without any deviation, just like building Legos blocks.

In addition, the project team chose to follow certain procedures in advance.The teamadopted locating clamps to directly cast the bearing pad stones on the bent caps in the prefabrication site, transported the optimized members to the construction site, as well as hoisted and installed the members through the bridge building machine. As a result, the construction period is largely shortened, and the previous 6-to-8-day-long installation of one bridge span costs 4 days now. So far, 18 bridge spans in the fully-prefabricated assembled part have been completed with their quality, safety conditions, and rate of process meeting the requirements, the plan of the integrated bridge building machine perfectly showing the industrial construction idea.

"In recent years, we don't see that the fully-prefabricated integrated installation technique is applied in many projects. We wish the new technique applied in this project can be spread in the whole country", the project leader said this about the future with confidence.