Geotechnics... an area of expertise fundamental to building the future
02 September, 2019
Every construction operation at ground level has its own geotechnical application
The range of techniques available for making soils suitable for construction projects includes:
- the retention walling that enables deep vertical excavation using techniques such as diaphragm walling and sheet piling
- the deep foundations that transfer the weight of buildings and structures to the ground using piles and bars
- the anchoring rods that nail structures into the ground and stabilise excavations by anchoring into stronger ground
- the injection of a reinforcement product through a borehole. When solidified, this product will consolidate and secure the soil, as well as filling cavities within it
- the sealing and pumping techniques used to control groundwater levels
- freezing, which solidifies the ground with temperatures below zero
- soil-mixing, which strengthens the natural soil by mixing it with a grout
- the soil improvement and reinforcement techniques that involve modifying soil characteristics using vibration and inclusion
- tunnel construction, which uses a variety of excavation and lining techniques
- and earthworks, which involve excavating, relocating and re-characterising soil to form embankments and other earthworks structures
Geotechnics... A buoyant market
"Space is at an increasing premium in our cities, which means that we are forced to build underground more and more often. Expertise in geotechnics then becomes essential”. Jean-Ghislain La Fonta, Executive Vice Presdient of Sixense
“The global market for geotechnical services is buoyant as trading and transport infrastructure projects, such as ports and metro systems, are multiplying”, explains Soletanche Bachy Executive Vice President Serge Borel. Jean-Ghislain La Fonta, Executive Vice Presdient of Sixense, completes the analysis: “This expanding market also presents many challenges, especially in urban environments. Space is at an increasing premium in our cities, which means that we are forced to build underground more and more often. Expertise in geotechnics then becomes essential”.
Minimising geotechnical risks through highly developed expertise and multiple technical skills
By dealing head-on with risks and transforming them into opportunities, VINCI Construction and its subsidiaries have developed expert skills across a wide spectrum of disciplines, from geotechnics for diaphragm walling to soil consolidation and tunnelling.
- The key technique of diaphragm walling developed by Soletanche Bachy is now a standard construction technique. It consists of building walls beneath ground level to provide safe working conditions for ongoing excavations
- Freyssinet offers anchoring solutions for structural stabilisation and soil reinforcement, as well as solutions for underpinning using micropiles and tie beams or injection.
- The success of Menard has been built on its development of Controlled Modulus Columns alongside other soil improvement techniques invented in-house
- Entrepose subsidiary Geostock specialises in the design and operation of underground hydrocarbon storage facilities. The company uses two main techniques: the excavation of salt-leached caverns and the mined rock caverns, which involve excavating rock at depths of around 100 metres. The pressure exerted by groundwater then provides assured containment of the hydrocarbon stored
- VINCI Construction Earthworks applies its expertise chiefly to linear constructions, such as roads and rail tracks. One of its goals is to reuse excavated material for future construction work to avoid the need to open new quarries
- Soil analysis technologies, particularly those that use the natural vibration created by cities to determine the nature of the subsoil,are the speciality of Sixense.
Flagship geotechnical projects
Now an important driver of growth for the Group, geotechnics has led the way in a number of high-profile projects:
- at Yamal in Siberia (Russia). Double-walled cryogenic tanks for liquefied natural gas storage sit on self-cooling foundations
- in Kuala Lumpur (Indonesia), with the Petronas Towers, whose foundations - the deepest in the world - were constructed by Soletanche Bachy
- in Dubai, for the construction of the future Creek Tower, which will be the highest in the world when completed
- near Paris, during works to transfer the load from the foundations of the CNIT in La Défense to hydraulic jacks as part of the project to excavate the huge underground Eole rail station for operator SNCF
- in Sweden, for the Hallandsås tunnel, which provides an outstanding illustration of the tunnel boring machine design expertise of VINCI Construction Grands Projets. The Group is also able to rely on the expertise of Bessac, a world leader in the field of mid-size and micro-tunnel boring machines.
International and R&D: geotechnics is driving two major growth areas
In every one of their operating locations, Group companies are innovating and adapting to build the structures envisioned by architects and planners.
“VINCI Construction has the densest concentration of geotechnical skills in the industry”, says Jérôme Stubler, Chairman of VINCI Construction. “Clearly, we have a strong presence in the basic geotechnical markets with brands like Soletanche Bachy, Menard and Botte Foundations, as well as in other disciplines where geotechnical engineering plays a central role, such as earthmoving and excavation”.
“VINCI Construction has the densest concentration of geotechnical skills in the industry.”Jérôme Stubler, Chairman of VINCI Construction.
But why not leave these high-risk operations to subcontractors? Jérôme Stubler explains the choice made by the Group: “It’s true that geotechnics does pose risks, but it also offers an opportunity when you have a good understanding of the field, but that itself requires enormous humility, because that understanding is based on parameters derived from highly fragmented knowledge. Our choice not to involve subcontractors has boosted the growth of the Group and extended our competence. Going forward, we will further expand this competence through international development and R&D to gain a more detailed understanding of soil structure, so that we can navigate it more effectively in terms of guiding the construction machinery resources we use”.