Geotechnical characterization of natural clays for the prediction of clogging risk for TBM

During mechanical tunnel driving it is known that the excavated soils can stick to metallic part of boring machine (TBM). Despite fact several test methodologies have been developed during last 15 years provide an assessment or quantification clogging risk, no standardized method available yet. This study evaluated three natural clay samples with different grain size distribution and mineralogical content considering two widespread set ups for evaluation tendency: Hobart mixing plate pull-out test. After a comprehensive geotechnical characterization samples, adherence force measured at water content/consistency index. Results show in terms $$w$$ consistency index $${I}_{C}$$ follow normal curves which, as percentage clay, minerals plasticity increases, higher amplitudes peak values. In general, existence correlation between classifications parameters behavior potential risk clays makes possible predict these risks design phase excavation plan appropriate mitigation actions.