Abstract Saprolites are highly weathered (W4) to completely decomposed (W5) rocks, with uniaxial compressive strength typically between 0.25 MPa and 5 MPa (≤ R1+). They retain the fabric of their parent rock and exhibit transitional mechanical behaviour between soils and rocks. For materials with a strength range between 1 MPa and 3 MPa (≤ R1-), as evaluated in this study, soil mechanics approaches are applied covering steps from undisturbed block sampling to triaxial test interpretation. A comprehensive approach is undertaken to determine the geotechnical behaviour of phyllite saprolites (Quadrilátero Ferrífero Mineral Province, Brazil), encompassing: (I) field characterisation and microscopic petrography; (II) specimen trimming with distinct angles between foliation and σ 1; (III) index property determination; (IV) consolidated undrained (CIU) and consolidated drained (CID) triaxial tests; (V) failure mechanisms analysis; and (VI) integrated data evaluation. Triaxial tests were categorised based on index properties, failure mechanism, deformational behaviour, dilatancy, and strength parameters. Saprolites with void ratio 1.2 displayed soil-like behaviour, including buckling failure, positive pore pressure, weathering grade W5, and variable deformational behaviour (elastic-plastic, strain-hardening/softening). The study provides correlations with prior work and analyses phyllite saprolites within the soil-rock transition framework, offering a foundation for further projects and geotechnical research.
Salgado et al. (Sat,) studied this question.