The Hangzhou Bay Bridge, which has been open for nearly 18 years, is making new moves: all 12 pile foundations of the first anti-collision pier in the bridge's anti-collision facility upgrade and renovation project have been successfully completed.

The project is China's first cross-sea bridge anti-collision facility upgrade and renovation project.

After the project is completed, the collision resistance of the main piers of the Hangzhou Bay Bridge will be upgraded from the 5,000-ton class to the 20,000-ton class, further reducing the bridge's operational risks and meeting the shipping needs of surrounding ports.

Recently, at the offshore construction site in Hangzhou Bay, accompanied by one powerful hammer blow after another, a large construction vessel was carrying out offshore piling operations.

"This project is China's first upgrade and renovation of anti-collision facilities for a cross-sea bridge. It will build 4 new anti-collision piers and supporting facilities at the north navigation channel of the Hangzhou Bay Bridge," said Mo Mingrui, head of the on-site work area.

It is understood that the Hangzhou Bay Bridge opened to traffic in May 2008. As its operating time has increased and the shipping economy of the Yangtze River Delta region has developed, the tonnage of vessels navigating beneath the bridge has grown larger and larger, gradually exceeding the bridge's designed anti-collision capacity of the 5,000-ton class. This construction was specifically implemented to fundamentally eliminate the collision risks brought by large vessel navigation.

The project has built a "four-in-one" anti-collision system for the Hangzhou Bay Bridge consisting of "flexible anti-collision facilities + independent anti-collision piers + ductile protection devices + bridge main towers."

"Simply put, dedicated anti-collision piers are being built on the outer side of the existing bridge main piers. The perimeter of the anti-collision piers is wrapped with 'energy-absorbing boxes,' and buffer devices are installed between the anti-collision piers and the main piers. Through layer upon layer of protection, a 20,000-ton-class anti-collision capacity is ultimately achieved," Mo Mingrui stated.

It is understood that the pile foundation construction of this project is being carried out beside the main piers of the bridge while it remains in operation, only 7.7 meters from the pier caps. The working space is extremely limited, and zero interference with bridge operations must be ensured amid strong tides and rapid currents.

To this end, the contractor selected "Zhuang 22," the only full-slewing piling vessel currently in service in China. During construction, it is positioned at 85° to the existing bridge and aligned with the current flow throughout, which keeps the vessel more stable, places the pile frame farther from the bridge structure, and avoids the problem of dragging anchor in cross currents, greatly reducing the risk of colliding with the bridge during construction.

"We plan to complete the construction of all 4 piers and 48 pile foundations by the end of May. After the typhoon season, we will begin pouring the offshore pile caps, and the entire project is expected to be fully completed by June next year," Mo Mingrui said.

Source: Haiyan Release

Original title: "First in the country, implemented in Haiyan, upgraded to the 20,000-ton class!"