On the morning of June 21, at the construction site of the Dongjin Yellow River Bridge by the Third Company of China Railway 14th Bureau Group, the last pile foundation of Pier 19 was completed as the final batch of concrete was poured into the tremie pipe. With this, all 130-meter ultra-long piles of the 19# waterborne main pier, a controlling works of the Dongjin Yellow River Bridge, have been fully poured.

The Dezhou Road West Extension and Dongjin Yellow River Bridge Project is an important supporting route of one of the "four horizontals" in Dongying City's "one ring, two expressways, four horizontals and four verticals" regional trunk highway network layout plan. It starts at the intersection of Dezhou Road and Haochun Road, extends westward along the planned Dezhou Road, crosses the Yellow River via a newly built bridge north of Xiaolizhuang Village in Lijin County, and then continues westward to the Rongwu Expressway connector. The planned construction period is 36 months. Once completed, the project will become a fast channel connecting the central urban area of Dongying with the Donglv Expressway, help accelerate the improvement of Shandong Province's highway transportation network, ease traffic pressure across the Yellow River, and speed up the development and construction of the Yellow River Delta Efficient Ecological Economic Zone and the Shandong Peninsula Blue Economic Zone.

The main bridge of the Dongjin Yellow River Bridge is the controlling works of the Dezhou Road West Extension and Dongjin Yellow River Bridge Project. It is a steel-concrete composite girder cable-stayed bridge with two towers and two cable planes and the largest span in the Yellow River Delta. The bridge is 880 meters long with a maximum span of 420 meters. The main towers use pile group foundations consisting of 50 bored cast-in-place piles, each 2 meters in diameter and 112 meters long. Construction is difficult, with many uncertainties and high safety risks.

"The waterborne pile foundation of Pier 19 is located in the main channel of the Yellow River. The pile drilling depth is 130 meters, comparable to the height of the Great Pyramid of Khufu. More than 48,000 tons of concrete are poured for the entire pier, requiring about 480 train cars to transport," said a person in charge of the Third Company of China Railway 14th Bureau Group. The geology in this section is mainly silty sand and silt, which is prone to hole collapse and cross-hole connection; ultra-long piles are prone to deviation; controlling the sand content of sediment is difficult; and underwater concrete has characteristics such as long pouring time and difficult quality control.

To ensure that waterborne pile foundation construction was completed before the Yellow River water and sediment regulation, project personnel worked around the clock with full effort. With the strong support of China Railway Dongjin Lijin Bridge Management Co., Ltd. and the full cooperation of Shandong Hengjian Engineering Supervision Consulting Co., Ltd., they completed the pile foundation construction task for the waterborne main tower pier on time and with high quality. "During construction, the project department boldly selected air-lift reverse circulation drilling rigs to improve hole-forming efficiency, used measures such as mud cyclones, vibrating sediment separators and secondary mud tanks to ensure hole-forming quality, and developed self-made slag fishing tools and rebar cage suspension devices to improve construction efficiency and save materials and costs," said Wang Xigang, technical director of the project.

According to reports, since drilling of the first pile of the 19# main tower began in late April this year, the builders of the Third Company of China Railway 14th Bureau Group have solved technical difficulties in the area such as difficult hole formation in silty sand strata, large scour, and easy hole shrinkage and deviation by optimizing construction procedures, rationally allocating construction resources, and developing efficient construction tooling. They completed the construction task of 50 pile foundations in 56 days.

The successful pouring of the waterborne pile foundations of the Dongjin Yellow River Bridge has laid a solid foundation for the subsequent construction of the main tower and created favorable conditions for the bridge to open to traffic on schedule. Next, the project department will carry out construction of the ultra-large waterborne cofferdam.