TECHNICAL | GROUND CONDITIONING
Right, figure 12: Foam system user
interface for Robbins 2014
WAYS INTO THE FUTURE
Soil Conditioning Testing Equipment During 2012 and 2013 we developed, together with the Norwegian Technical University, in Trondheim (NTNU), a quite simple, laboratory-scale boring machine capable of drilling through compacted soil samples (Langmaack 2013). Soil conditioners can be added at the simplified cutterhead and torque as well as thrust values can be recorded online, and the cutterhead tool wear recorded after finishing the test. We call this machine ‘Soft Ground Abrasion Tester’
Below, figure 13: SGAT FIR comparison
(SGAT) and it represents, in fact, the missing link between standard laboratory mixing tests and the soil
TBM parameters with FL04: FIR=30 vs FIR=50
conditioner application on site. The SGAT tester enables us to better identify the best product alternatives as well as the best injection ratio, even considering the resulting wear. Figure 13 shows easily interpretable results of using the same compacted soil and same advance parameters with two different FIRs. This system deserves further development and consideration – for the chemical industry, for the construction companies as well as for the consultants and their clients.
Special thanks to Pål Drevland and Filip Dahl for realising all the good ideas we had.
Thrust (N) Torque (Nm)
Preserving the Environment Our all overall task is to preserve the environment, doing so in tunnelling with soil conditioning to minimise the impact of the chemicals and agents on ground surrounding the excavation and on landfill from disposed spoil. Special risk assessments, like those already in place for Copenhagen metro development for example, are a great step forward. Preserving nature is about more than just looking at biodegradation values (Langmaack 2023). It is important to indicate here that more
Wear (mg) 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 16 | November 2023
environmentally-friendly soil conditioning products are available these days on the market but not always used due to their slightly higher costs – which touches upon the next very important point – a strategic perspective, taken together by key parties developing a project – the client, contractor and consumables producer.
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