Methods used to construct underwater pile caps on the Hong Kong–Zhuhai–Macao Bridge

The embedded pile-cap design in the Hong Kong–Zhuhai–Macao Bridge project meant that prefabricated pier shafts and pile caps had to be installed under water. This posed a host of daunting construction-related challenges. The designer for the bridge – the Highway Planning and Design Institute, Beijing, China – proposed a method using temporary retaining structures to assist in the underwater installation. According to the local hydrogeological conditions and the capacity of the equipment available in each section, three methods of construction for these temporary works were used. Following completion of the project in 2018, this paper provides a technical comparison of the three methods with the aim that it will serve as a reference for similar projects in the future.