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Bauer Technologies is an expert in the foundations sector and is well known for the installation of vertical tunnelling foundation elements. A landmark project was the installation of the three up to 120m deep diaphragm wall shafts, with diameters of between 8m and 35m at Woodsmith mine in Whitby, North Yorkshire, which is recognised as the biggest mining project in Britain for decades.
Additionally, Bauer Technologies is a specialist contractor for horizontal drilling, as part of underpass construction and globally Bauer has installed over 25
underpasses since 2001. Bauer Technologies works in close cooperation with other Bauer subsidiaries and Bauer’s head office in Germany, as well as with a wide range of specialist equipment and material suppliers, ensuring access to the latest technology and expert knowledge.
Tunnelling options
There are of course several conventional tunnelling options, such as open trough construction, cast insitu; piled retaining walls and cast insitu roof slabs to create box structures and the jacking of prefabricated tunnel sections.
The latest and most up to date technology uses innovative equipment, processes and skills to improve on these options and develop capabilities previously out of reach, within the sector. One significant example of this is Bauer Technologies’ pipe arch, or grouted arch tunnel. The pipe arch provides a temporary, structural envelope and enables tunnel excavation and installation of the permanent lining. The pipe arch also supports the overlying ground, as well as
infrastructure, during tunnel excavation – thus minimising associated surface settlements. The major advantage over conventional construction methods for installing underpasses such as retaining walls with a cast insitu roof slab and box jacking lies in the fact that traffic flow is not obstructed by the pipe arch construction. Additionally, when working in granular material and within the groundwater table, a grouted arch constitutes the most efficient technique to control ground movement and water ingress.
Bauer Technologies tunnelling capabilities
With Bauer Technologies’ innovative techniques, tunnels can be constructed up to 240m in length with precision and at pace with work undertaken from either end. Despite the scale of such projects, an accuracy of plus or minus 20mm over 100m can be maintained.
Whatever the scope or size of the project, Bauer can leverage these technological advances and offer several options for general tunnel-related works. Bauer’s team can install retaining walls (secant pile wall or diaphragm wall) for tunnel boring machine (TBM) portals. As well as retaining walls, it can install deep shafts for TBM access or egress or for post construction ventilation, servicing and emergency exits. Bauer can also offer ground treatment options for tunnel cross passage construction. These include grouting, soil freezing, dewatering or forepoling – which uses casing tubes drilled through the overburden to form a pipe arch filled with grout – and ground treatment for TBM launch and retrieval platforms.
Advantages
Taking advantage of Bauer Technologies’ techniques delivers a number of benefits. With the pipe arch supporting the overlying ground, construction can take place less than a metre below ground with minimal disruption experienced by road or rail users. This important advantage means that the time required for the project is reduced, along with the associated savings in staffing, lighter plant needs and the minimised environmental impact.
Technical advantages of Bauer Technologies’ diaphragm wall techniques include high levels of accuracy through optical survey and steerable cutting head, full dewatering control, shafts that can be integrated to the final structure and a minimised risk of surface settlements.
Project Examples
One example of a recent Bauer drilling project is the directional drilling and injection for a 64m long pedestrian tunnel at the Doha Corniche. The Doha Corniche is a waterfront promenade extending for 7km along Doha Bay in Doha, the capital city of Qatar. From a newly constructed car park, a pedestrian tunnel had to be constructed under the Corniche to link the car park to the waterfront promenade. The total width excavated under the Corniche was 9m before any shotcrete and concrete was poured.
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