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Product category: Ground Engineering
News Release from: Aarsleff Piling | Subject: Specialist piling contractor
Edited by the Buildingtalk Editorial Team on 05 July 2006

Aarsleff piles into Arup campus

Specialist piling contractor Aarsleff Piling has installed driven precast concrete piles for a major extension to the Arup Campus offices at Blythe Valley Park in Solihull.

Specialist piling contractor Aarsleff Piling has installed driven precast concrete piles for a major extension to the Arup Campus offices at Blythe Valley Park in Solihull with little disruption to the activities of this busy office Piling took place within 10m of the fully occupied offices

Acoustic and vibration tests carried out by Arup and Aarsleff showed results that were within acceptable limits.

"There was some concern when the piling first started that the noise and vibration could cause possible damage to our existing office building and disruption to its occupants," said Ove Arup and Partners director Nick O'Riordan.

"As members of the design team for the extension, we worked with Aarsleff on a technical level through the main contractor Laser Build to produce a reasonable method of working in an attempt to minimise impact of the piling on the building and its occupants".

"Aarsleff did some noise and vibration monitoring and we did some acoustic testing to see how the building was behaving and were able to confirm it was partly a perception problem rather than a technical matter".

"This showed us that with appropriate acoustic checks and controls, driven piling with modern equipment can be used very close to occupied buildings".

"There has to be careful planning and communication in advance to ensure the normal concerns about noise and vibration can be allayed and put into context, particularly as the velocity of sound in soil, air and through the building fabric is different".

"When you have repetitive hammering you can hear the hammer strike and then feel the ground vibrate milliseconds later, which can be disturbing in an office working context".

"But once we had established that this was partly a perception problem piling then proceeded very rapidly and smoothly".

The new two storey extension building was designed by Arup Associates for developer client British Land.

The foundations were designed on the basis of site investigations carried out for both the first and second phases of the Arup Campus.

The first phase was also built on driven pile foundations and combined two of Arup's previous centres into a single multi-disciplinary office hub with particular focus for infrastructure, building and consulting services projects.

Laser Build was awarded the approximately £6.5M, one year building extension project by British Land based on tender documents specifying driven or auger piling for the foundations.

However, during subsequent negotiations between Arup and Laser Build it was decided to opt for driven piling to support the extension".

"Although it was unusual to use driven piling next to an existing building, it proved to be the most cost effective solution," said Laser Build project manager Chris Wilson.

Aarsleff, working for Laser Build, won the supply, handle pitch and drive contract on open tender to install a mixture of 250 mm and 300 mm square section continuously reinforced precast concrete piles in groups of twos and threes for working loads up to 750kN.

Using the original site investigation data, collected for the first phase of the Arup Campus, together with additional information gained from trial pits dug in the extension area, Aarsleff did the final design based on piles up to 11m long.

However, prior to a start on piling Aarsleff probed the site down to 15 m and drove a test pile to confirm ground conditions and to establish piles could take the designed working loads.

At this point Arup raised its concerns about noise and vibration and piling was temporarily halted while awaiting results from the monitoring and test loading.

Results from the test loading enable Aarsleff to redesign and shorten to 6m the continuously reinforced precast concrete piles, which were made by its subsidiary Centrum Pile.

Aarsleff, using one of its own Banut 700 self erecting, hydraulic fixed leader piling rigs with a 5t drop hammer, drove the 110 piles through clay to found into underlying dense sands and gravels".

""Aarsleff saved us a lot of time and potential delay, as the piles were shorter and installation was much faster," said Chris Wilson".

""They were driving about 40 piles/day in a 9 hour to 10 hour day and completed the installation in just three days, instead of the originally anticipated two weeks".

"Aarsleff did a very good job".

"I'm very pleased and can't fault them." After installation the precast concrete piles were statically and dynamically tested by the independent testing company Precision Monitoring and Control".

"The use of precast and preformed elements, including foundation systems, can result in a highly sustainable way of construction," says Nick O'Riordan".

"It was a pleasant coincidence for us that Aarsleff, having successfully installed the 600 mm square section precast piles for the piled slab, which Arup engineers (working with Halcrow and Bechtel as part of the Rail Link Engineering consortium) designed for the Channel Tunnel Rail Link project across the Thames Marshes, is also doing the work for our office extension".

"We know Aarsleff and the high technical quality they bring to projects, which we obviously find reassuring".

"We expect to move into our extension on schedule towards the end of 2006.".

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