China Achieves Milestone in Underwater Tunnel Construction

The Yellow River tunnel in Jinan, Shandong province, has reached a significant milestone with the completion of its upper deck. This achievement marks a major advancement for the world's largest-diameter underwater shield tunnel, as reported by Xinhua, the Chinese state news agency. The upper deck was finalized with the pouring of the last cast-in-place roadway slab, according to the Global Times, a state-owned newspaper.

Newsweek

The Yellow River tunnel spans 5.75 kilometers (approximately 3.6 miles) and features six lanes across two levels, with a speed limit of 60 kilometers per hour (around 37 miles per hour). Notably, about 3.3 kilometers (around 2 miles) of the tunnel were constructed using the shield tunneling method, employing a 17.5-meter diameter (around 57 feet) tunnel-boring machine (TBM). This continuous excavation of 2 miles was accomplished without cutterhead replacement, a feat deemed unprecedented under such conditions.

Newsweek

The project has set records for 17-meter-class shield tunneling, achieving a peak daily advance rate of 18 meters (around 59 feet) and a monthly advance of 426 meters (around 1,397 feet). Zhou Xiang, a senior engineer with China Railway 14th Bureau Group and the project's chief technical expert, emphasized the complexity of constructing the upper slab within the confined space of the shield tunnel, where precision is critical. He stated, "Positioning errors must be controlled within millimeter-level tolerances."

Newsweek

To address the challenges of tunnel construction, the project team implemented a modular design and an independent traveling system. This approach facilitated the precise installation of various embedded components and enhanced overall efficiency. Multiple platforms operated in parallel, creating an assembly-line process for reinforcement binding, formwork installation, and concrete curing. Additionally, a dedicated lower-level transport corridor was established to ensure the smooth flow of materials and workers throughout the construction site.

Newsweek

The completion of the Yellow River tunnel is expected to significantly improve transportation infrastructure in the region, enhancing connectivity and potentially stimulating economic growth. As the first single-bore, double-deck shield tunnel to pass beneath the Yellow River, this project represents a notable engineering achievement for China and sets a precedent for future infrastructure projects.

Newsweek

• "Construction of the upper slab takes place within the confined space of the shield tunnel, where numerous embedded components of varying types must be precisely installed." — Zhou Xiang, Senior Engineer, China Railway 14th Bureau Group

Newsweek

• "Positioning errors must be controlled within millimeter-level tolerances." — Zhou Xiang, Senior Engineer, China Railway 14th Bureau Group

Newsweek

The Yellow River tunnel project exemplifies China's commitment to advancing its infrastructure capabilities through innovative engineering and construction techniques.

Newsweek