Equipment & Techniques
Bauer GB50
The GB50 is a specialized diaphragm wall grab system, equipped with hydraulic grabs. Wall thicknesses can range from 600mm to 1500mm, and excavation depths can go up to 80m. Despite its large capacity, the machine has a limited size, which means that diaphragm wall work is also perfectly possible in an urban environment or in construction pits with space limitations.
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Measurement and registration system: D&S uses 2 different, independent systems to continuously monitor the exact position and orientation of the diaphragm wall grab. Both Bauer's built-in sensors and the well-known 'Jean-Lutz' system are present on our grab. In this way, we are always able to correct the excavation process at the slightest deviation, and then draw up a detailed report of the completed structures.
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Turning mechanism: The hydraulic grab is equipped with the TD4 Turning Device, which allows very precise unloading of soil into dumpers and skips, ideal when space is limited. This 'Turning Device' also allows the execution of complex geometries, in which the grab carrier cannot be aligned perpendicular to the excavation.
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Propulsion: CAT's Stage V engine guarantees a low fuel consumption and low noise emissions. An automatic registration system allows to monitor fuel consumption in real time, which makes it possible to accurately manage and optimise the economic and environmental impact of the works.
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Correction mechanism: The DHG V grab is equipped with 8 steering flaps to make precise corrections in the excavation trajectory, so that a perfect result can be achieved even in highly stratified and challenging soil conditions.
Description
Bauer GB50
The grab is equipped with correction mechanisms to ensure maximum verticality. Various sensors continuously measure the exact position of the grab and hydraulic cylinders allow the direction to be corrected if necessary. This means that even in challenging ground conditions, a very precise execution is possible.
The diaphragm wall excavator is equipped with a modern, Stage – V engine with low fuel consumption, and thus fits in with the sustainability ambitions of D&S and its founding companies.
The diaphragm wall machine can be effortlessly converted to a ‘low head’ version, enabling the construction of diaphragm walls in spaces with working height limitations as low as 6 meters. This adaptability allows for operations under viaducts, buildings, and overhead cables and pipes.
Other equipment
D&S consistently invests in cutting-edge equipment and isn’t afraid to innovate its own machinery and techniques. This commitment allows us to provide the most economical and high-quality solutions, even for complex projects and challenging working conditions.
D&S can also dispose of a variety of equipment such as Liebherr excavators, various de-sanding equipment and grapple equipment as well as bentonite plants.
Applications
Hydraulic engineering and marine infrastructure
Diaphragm walls are capable of supporting large loads, thus forming ideal solutions in projects with high earth-retaining heights, or large horizontal or vertical loads. Examples are quay walls and large (sea) locks. For example, D&S staff were involved in diaphragm wall construction projects such as the new lock in Terneuzen, or in the realisation of quay constructions in Port-la-Nouvelle.
Tunnel construction
Diaphragm walls are frequently used in the construction of tunnels, in the creation of very deep construction pits or as a tunnel walls. D&S staff were involved in the execution of diaphragm walls and CB walls in various projects in Belgium and the Netherlands, such as the Oosterweel Connection in Antwerp.
Urban environment
Diaphragm walls are ideal solutions when strict control over earth movements is required. The technique allows for the construction of foundations right next to existing structures, such as architectural heritage sites, where even minor displacements can have significant consequences. Additionally, the process is vibration-free and almost noise-free, minimizing disruption to residents.
Technique
- The execution of diaphragm walls or CB walls always starts with the construction of the guide walls: two parallel reinforced concrete walls following to the route of the final foundation. These are used for guiding the grabs, allowing the support fluid to be kept on level and supporting the steel reinforcement cages when placed in the trench.
- The excavation of the panels is executed with mechanical or hydraulic grabs. During the excavation process, the open trench is filled with a ‘support fluid’ to ensure that the walls of the excavation do not collapse. This support fluid can consist of a mixture of water and a special type of clay (bentonite), but modern polymer products are also frequently used, so that an optimal mixture can be selected for every soil condition. In the case of CB walls, the support fluid will eventually harden and form a low permeability cut-off screen.
- After reaching the final depth, the diaphragm wall panel can be fitted with a reinforcement cage. These are prefabricated in a workshop and suspended in the trench on site with an auxiliary crane. The reinforcement cage can be equipped with additional items, such as tubes for anchors or measuring pipes for cross hole sonic inspection of the wall and joint quality. A steel formwork can be placed between panels, equipped with a flexible joint tape that makes the transition between two neighbouring panels more watertight. Connections with sheet piles or combi walls are also possible.
