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Liebherr’s various divisions breaking ground all over the world 

By Jill Harris, Piling Canada

Introduction
At the end of October, Liebherr-Werk Nenzing GmbH invited me to attend their annual Liebherr Information Tour for the International Construction Trade Press. The event took place over the course of a few days in Germany and France, with about 40 participants from 13 different countries from the around the world. Piling Canada was the only Canadian publication represented.

On Oct. 22, I flew from Winnipeg, Man. to the airport in Frankfurt, Germany. After lunch, our group took a bus to Darmstadt, the location of the construction of a new particle accelerator, the Facility for Antiproton and Ion Research (FAIR) in Europe. Professor Boris Sharkov, the scientific managing director at FAIR, Dr. Markus Bernards, public relations officer at FAIR, Dr. Florian Hehenberger, director of site & buildings at FAIR and Johannes Rhomberg of Liebherr explained the facility, the building process and equipment technology of the impressive construction undertaking.

FAIR: the project
FAIR will be one of the world’s largest research facilities. The project, expected to cost around 1.6 billion euros, is being funded by international shareholders; the Federal Republic of Germany together with the state of Hesse is assuming close to three-quarters of the cost, with remaining shareholders responsible for the rest. Such a massive project can only be realized with international cooperation, and among FAIR shareholders are Finland, France, India, Poland, Rumania, Russia, Slovenia and Sweden, as well as Great Britain, an associated member of FAIR GmbH.

Following the anticipated completion date of 2018, scientists will use the particle accelerator to examine the development of the universe, from the “big bang” to today. Other plans for the facility include developing new medical therapies and diagnostic methods as well as energy-efficient high-performance computers and new materials ( for interplanetary space travel, for example).

More than 3,000 scientists from around the world will visit FAIR each year once the construction is complete to conduct a wide range of experiments, focusing on questions surrounding the building blocks of matter, such as the origin of elements or how matter reacts under extremes of pressure and temperature.

Such a sophisticated purpose requires a sophisticated building. A ring accelerator with a circumference of 1.1 kilometres will form the heart of the FAIR complex. 24 buildings and tunnel sections will provide more than 62,000 m2 of usable space and enough room for 3.5 kilometres of beam control tubes and huge detectors with complex technical infrastructure. Approximately 35,000 tonnes of steel and 600,000 m3 of concrete will be used to build the facility. At peak times, as many as 600 construction workers, technicians and engineers are employed on the site. This heavyweight construction – with metre-thick walls, in some places – requires solid foundations. Liebherr machines were the choice foundation equipment.

Challenging ground conditions
Geotechnical engineers carried out extensive preliminary subsoil surveys to learn about the composition, as it plays a key role in determining settlement behaviour. In all, the structures should settle as evenly as possible within a predictable timeframe.

68 exploratory bores were drilled at depths between 35 and 80 metres, while more probing tests were done with a heavy penetrometer to determine how compact the soil was. More tests for further site compactness, consistency and permeability were completed to establish how groundwater levels will rise and fall. In all, 250 soil samples were taken and examined to predict settlement behaviour.

The geotechnical engineers discovered that the first 20 metres of the subsoil consisted of sand and silt, while clay was found up to a depth of 75 metres. These layers are largely composed of compressible materials – their density changes when subjected to heavy pressure.

Additional exploratory tests were completed between August 2011 and January 2012; three pile load tests on 22-metre (maximum) bored piles at different depths demonstrated how the piles would behave under the pressure of the heavy buildings. A five-metre-high trial embankment on a 20 by 20-metre surface was monitored for six months. In conclusion, the load exerted by the buildings on a foundation base would result in medium-range settlement of between 10 and 35 centimetres.

Foundation design to reduce settlement 
The geotechnical engineers determined the load-bearing performance and deformation behaviour of the subsoil using 3-D finite element calculations, which inspired the final foundation design.

The final design consisted of a combined pile-raft foundation for all facilities apart from the accelerator ring. An advantage of this foundation compared to a plain base foundation is that settlement-over-time behaviour is usually less pronounced with this type of foundation. In the case of the FAIR complex, the buildings will be more or less settled one year after the construction work is completed.

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Piling Canada is the premier national voice for the Canadian deep foundation construction industry. Each issue is dedicated to providing readers with current and informative editorial, including project updates, company profiles, technological advancements, safety news, environmental information, HR advice, pertinent legal issues and more.