Development of the Soft Ground Abrasion Tester (SGAT) to predict TBM tool wear, torque and thrust

• Tool life measured by the SGAT is highly influenced by the soil compaction, rpm and water content.
• There is a good correlation between measured steel wear and torque in the SGAT apparatus.
• Benefits of soil conditioning additives for TBMs can be measured and quantified by the SGAT.

The Norwegian University of Science and Technology (NTNU), SINTEF Rock Engineering and BASF Construction Chemicals have jointly developed a new test device called the Soft Ground Abrasion Tester (SGAT). The ambition and purpose of the design of the test and the applied test procedure is to replicate an in situ soil – TBM excavation tool contact, in a small and simplified scale. The current development is attempting to bridge a gap when it comes to estimating soft ground and soil abrasivity, as earlier research on e.g. the NTNU/SINTEF Soil Abrasion Test™ (SAT) shows that it does not catch up all driving factors for soft ground and soil abrasivity directly. The paper summarizes the development of the SGAT apparatus, and shows its capabilities to evaluate, quantify and compare how the soil mineralogy, water content, pressure, compaction, and the use of soil conditioning additives influences the wear rate on the SGAT excavation tool. During testing the required torque and thrust are monitored and logged, making it possible to measure various soil–soil conditioning matrixes requirement for operational parameters.