Bachy Soletanche Ltd - Completes ground works for addition to
Birmingham’s business district
One of the UK’s largest city centre
schemes under construction outside of London has
recently undergone preparation works with the completion
of the piling contact led by geotechnical specialist,
Bachy Soletanche Limited (BSL). The project, at Snow
Hill in Birmingham, is a 96,000sq metre mixed use
development set in the heart of Birmingham’s business
district, featuring two towers that contain residential
apartments and a five star hotel.
The piling works contract, worth in of excess of
£1.5million, commenced in July of this year and required
the installation of 220 linear metres of anchored
contiguous piled wall. The wall consisted of 241
No.750mm diameter piles, drilled to an average depth of
17metres. These piles are anchored back with 70 No.
temporary ground anchorages to form the perimeter
retaining wall which will be excavated to create a
five-storey basement car park.
The ground conditions were an important factor when BSL
designed the retaining wall solution for the project.
The ground profile is made ground, sand and sandstone
varying from depths of 2metres below ground level to
13.5metres. As a result, BSL designed a piled wall
solution for the client, utilising two separate piling
techniques, as Steve Mallinson, contracts manager for
Bachy Soletanche Limited commented:
“Some parts of the wall had to be drilled using a cased
Large Diameter Auger (LDA) rotary bored piling method,
while other parts of the wall have utilised the more
cost effective and timely, Continuous Flight Auger (CFA)
method.
This is a result of extensive probing that we carried
out on the development, and due to the length of the
rock sockets required, it has been necessary to use a
combination of both CFA and LDA to form the contiguous
piled wall.”
Alongside the contiguous piled wall, BSL has also
constructed 10No. 1200mm diameter LDA plunge column
piles and 14No. 750mm diameter bearing piles.
In addition to the piling works, BSL had to undertake
the coring out of obstructions, such as the reinforced
concrete slabs that formed part of the historic system
of subways and underpasses on the site. These
obstructions could not have been dug out simply by an
excavator, due to the sites location on a major traffic
junction; and piles located right on the site boundary
had to be cored out with piling rigs to ensure the
adjacent roads and services were not undermined. The
history of the site, city centre location and the
sharing of site access with another contractor from an
adjacent site have made logistics problematic.
Steve Mallinson continued:
“As two heavy duty Bauer BG-22 rigs were used on the
project, along with service cranes and all other
essential plant and machinery, the site required careful
co-ordination to enable the smooth running of the work
which was surrounded at all times by pedestrians and
traffic.”
BSL effectively took on the role of main contractor for
installation of the piles. In this capacity BSL were
responsible for the provision of welfare and offices,
setting out, crane and excavator hire, spoil disposal,
security and breaking down the piles upon completion.
“As the sole contractor on the site, we have worked very
closely with the client to ensure that the project has
run on course. And now that the piling work is finished,
the contiguous wall will be excavated; then we will
revisit the project to install temporary ground
anchors.” Concluded Steve Mallinson.
The full project is due for completion at the end of
2008, with the Snow Hill development set to become one
of Birmingham’s most prestigious landmarks.
Email:
fiona@manifestcomms.co.uk
Arundel Jones Associates Ltd
Hill Farm, Linton Hill, Maidstone, Kent ME17 4AL
Tel : 01622 745333
news@buildingdesign.co.uk
Registered in England and Wales No. 07334149
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