GROUND CONDITIONING | TECHNICAL


Triangle: Client, Contractor, Consumables Producer Looking back to projects like BPNL Lyon in the late 1990s being the germ cell of many modern soil conditioners, it may now be time for the next significant step forward. In order to make this happen, construction companies as well as clients might act slightly less conservatively, be more open towards new possibilities, less price/kg but more solution driven which will surely lead to an overall benefit. This includes the acknowledgement of a good technical on-site service. Furthermore, big projects should include funded


research, part-linked to university and industry to help drive innovation forward and also enable well-founded and independent back-analyses.


Future Products and Systems Here are just some ideas: ● The use of foam on hard rock TBMs definitely needs further research and development, and university support. Foam reduces dust much more efficiently than just sprinkling water and, in addition, also wear can be reduced much more efficiently using the right anti wear polymers. We have seen these encouraging advantages already on a few selected jobsites but the real breakthrough is still missing.


● The SolidFoam® technology will ensure a higher level


of soil conditioning efficiency as well as tunnelling security when driving through fault zones or sections of increased soil permeability in either mixed or full face conditions.


● The DrainGrout®


, MC-Bauchemie technology opens


new horizons and brings a 2-component annulus grout to the market with permeabilities of 10-5 10-4


m/s for water draining purposes.


● The Automatic Foam System, which will ease the work for the TBM driver, will deliver more uniform TBM drives and hopefully limit the incorrect application of soil conditioners. Special thanks to Tim Babendererde for believing in this system and being a great sparring partner.


SUMMARY Soil conditioning has seen enormous development over the past decades – allowing faster and more secure EPB-TBM drives in clay soils, in areas of high soil permeability as well as enabling all kinds of mixed face conditions and huge TBM diameters. The application range of EPB TBMs has never been so vast as nowadays – the possibilities of limiting surface settlements to an absolute minimum have never been so extensive. Nevertheless, the wide-spread mentality of just


looking on the price/kg of the soil conditioners impedes their real efficient use in the day-to-day business – it also impedes further R&D of soil conditioners. The real benefit of well-developed and applied soil conditioners must be calculated correctly, finally, and dedicated research budgets associated to big tunnelling projects would help significantly in driving innovation forward. New Automated Foam Systems will hopefully simplify


the tasks for the TBM driver by early alert of improper soil conditioning use and proposing counteractions – optimising the soil conditioning in general.


m/s to


REFERENCES ● Maidl et al (2012) Mechanised Shield Tunneling, ISBN 978-3-433-60150-1


● Greeman (1994) Milan 1994: Ground Engineering, Vol: 27, Issue Number: 9 Publisher: EMAP CONSTRUCT LIMITED, ISSN: 0017-4653


● Langmaack, L. (1997) Optimierung des schaumgestützten EPB-Vortriebes: BPNL Lyon, STUVA Tagung Berlin, Alba Verlag Berlin 1998 Vol 37, pp88, ISBN 3 87094 636 9


● Langmaack, L. (2002) Soil Conditioning for TBM: Chances & Limits, AFTES Toulouse 2002 ISBN 951 04 1624 ● Langmaack, L. (2005) Soil Conditioning for EPB machines: balance of functional and ecological properties, ITA Istanbul 2005, A.A. Balkema Publishers, Leiden, 2005, ISBN 9780415889315


● Langmaack, L. (2008) Erddruckgestützter TBM Vortrieb – Chancen & Risiken, ETH Symposium Zuerich, published by Felsbau Magazin 2008, page 149, Heft 3


● Langmaack, L. (2013) ITACET seminar Sao Paulo, 26-27th April 2013 ● Langmaack, L. (2013) Development of the Soft Ground Abrasion Tester SGAT Tunneling and Underground Space Technology 38, pp. 398-408, http://dx.doi.org/10.1016/j.tust.2013.07.021


● Langmaack, L. (2016) Difficult ground conditions? Use the right Chemicals!, Tunnel Underground Space Technol. 2016, http:// dx.doi.org/10.1016/j.tust.2016.01.011


● Langmaack, L. (2017) EPB Tunneling in hard rock conditions and transition zones. World Tunnel Congress 2017 Bergen, Norwegian Tunnelling Society, ISBN: 978-82-92641-40-8


● Thewes (2023) WTC Athens 2023, Expanding the application range of EPB shields using SolidFoam, ISBN 978-1-003-34803-0 ● Langmaack, L. (2023) WTC Athens 2023, Frankfurt U5 Metro Extension, ISBN 978-1-003-34803-0


November 2023


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