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Client: The Noble Organisation, Gifford & CMP

Site: The Brighton Palace Pier – Boat Deck Replacement

Location: Brighton, East Sussex, United Kingdom

Project Description

Brighton Palace Pier is a Grade II listed

building that opened in 1899. The pier stem

and head total approximately 540m in

length and the pier head itself comprises

structure from three distinct time periods.

The central core comprises Victorian cast

iron piles. To the north east corner is an

area known as the boat deck built in the

1930’s. In the mid 1990’s the pier head was

extended with new structure that

surrounded the original pier head. The 36

piles to the 1930’s boat deck are rolled steel

joists. Interestingly GTL’s initial involvement

came from the fact that the original

Victorian piles were screw piles.

GTL were commissioned to design, supply

and install a piling solution for the boat deck

replacement project. The clients engineer

had originally planned to utilise helical piles,

however, GTL were able to provide an

alternative unique solution that would

ensure buildability and provide cost savings

to the client. The new solution had never

before been used in this environment and

under such constraints anywhere in the UK.

Specific working restrictions made this

particular project a challenge. The Pier itself

is a commercially operating pier that

attracts large numbers of public visitors. The

design was developed to negate the need

for access / working from the sea to reduce

any potential delay due to poor weather and

also mitigate potential health and safety

hazards.

A structural working platform was constructed

below the pier deck to enable access to install

the piles. This obviously created working

height, logistical and load restrictions;

therefore, the piles were designed in

manageable sections.

Geotechnical Ground Conditions

GTL, in partnership with Whitworth Peck,

reviewed the available soils data which

revealed that the site was underlain by thin

seabed gravels overlying Upper Chalk. The

chalk was typically described as a very

weak/weak low and medium density chalk.

On this basis, GTL treated the chalk

encountered as “rock chalk”

Pile Design

The scheme required 24 bearing piles each

consisting of a 406.4mm x 20mm thick

circular hollow section installed in conjunction

with a limited access segmental auger.

© GTL Partnership Ltd • Tel +44 (0)1403 741 166

Compression loads varied, peaking at

1,300kN. In addition, there were significant

shear and moment loads, with some minor

tension loads.

The working platform was positioned 10m

above the seabed and only 5m below the

pier deck. The first pile section, 5m long,

was placed within a specially designed piling

gate and suspended above the sea while the

other sections were connected via a flanged

connection and lowered through the piling

gate. This process was repeated until there

was sufficient pile length to transfer the load

from the working platform to the seabed.

The CHS pile was then rotated into the chalk

bed with a rotary piling rig to a depth of 5m.

Additional sections were then added to

achieve the designed embedment of the CHS

pile. The centre of the CHS was then drilled

out by a segmental auger piling rig and the

pile was progressed to 15m design depth. The

pile shaft was then grouted and the centre of

the pile was reinforced with an Ischebeck bar.

Acknowledgements

Senior Management

Gavin Rixon – Project Director

Barnaby Tanner – Commercial Director

John Whitworth – Geotechnical Consultant

Karsten Richter – Lead Design Engineer

Mark Stacey – Construction Manager

Thanks to all of Mark’s team who worked

under extremely challenging conditions and in

harsh weather to deliver a successful project,

one that GTL is rightly proud of.

GTL used Oasys software in particular ALP

(Analysis of Laterally Loaded Piles) to predict

the pressures, horizontal movements, shear

forces and bending moments induced in the

pile when subjected to lateral loads, bending

moments and imposed soil displacements.

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