Dublin Port Cross Berth Quay

The works formed part of the wider Alexandra Basin Regeneration Project and involved the construction of a new combi-wall and contiguous piled tie-back wall.

Due to the challenging Dublin Boulder Clay and the requirements of the permanent works design, a bespoke sequence of enabling and piling works was developed by Quinn Piling’s engineering team.

Piling Scope and Details

Quinn Piling’s works included:

• Installation and mucking-out of 110 no. 1,800mm diameter temporary pile casings
• Temporary casings installed to depths of approximately 27m
• Enabling works for the installation of 1,400mm diameter permanent steel tubular piles
• Installation of sheet piles between the permanent tubular piles
• Installation of 183 no. 750mm diameter CFA piles
• Construction of a contiguous piled tie-back wall
• Design and manufacture of bespoke pile-gate equipment
• Value engineering and manufacture of reinforcement cages

The large-diameter piling works extended through the Dublin Boulder Clay, with the permanent tubular piles subsequently driven approximately 9m deeper.

Challenges

The principal challenge was installing the combi-wall through the difficult Dublin Boulder Clay.

The permanent tubular piles could not be installed solely by driving, requiring Quinn Piling to develop an alternative methodology. Accurate positioning, verticality and rotation of the tubular piles were also critical to ensure the sheet piles could subsequently be installed between them without the risk of de-clutching.

Solution

Quinn Piling developed a sequence involving the installation and mucking-out of 1,800mm diameter temporary casings through the boulder clay. This allowed the permanent 1,400mm diameter tubular piles to be pitched within the temporary casings and driven to their final depth.

A bespoke pile-gate was designed and manufactured by Quinn Piling to control the position, verticality and rotation of each permanent tubular pile. This provided the accuracy required for the later installation of the sheet piles forming the combi-wall.

The works were carried out using Quinn Piling’s MAIT HR 420- 800, 140-tonne piling rig, together with a large-diameter pile oscillator used to withdraw the 6m long segmental temporary casings. This allowed the piling rig to remain focused on casing installation and excavation, helping to reduce the overall programme duration.

For the tie-back wall, 183 no. 750mm CFA piles were installed to form a contiguous piled wall. Quinn Piling also value-engineered the reinforcement cages before manufacturing them at its automated cage manufacturing facility in Downpatrick.

Outcome

The project brought together large-diameter rotary bored piling, CFA piling, preboring and sheet pile installation within a challenging marine environment.

Through the development of a bespoke installation methodology and purpose-built equipment, Quinn Piling successfully delivered the piling works required for the new berthing infrastructure at Cross Berth Quay.