Abstract
This paper evaluates the liquefaction potential of tailings within a critical structural zone of an upstream tailings storage facility founded on high-plasticity clay. The study used cone penetration testing with pore pressure measurement (CPTu) as the primary method for assessing the insitu state of tailings, supplemented by laboratory tests and inverse numerical modeling. Tailings samples are characterised through triaxial tests to calibrate NorSand parameters, enabling the comparison of empirical screening methods such as Robertson (2022), Plewes et al. (1992), to the more advanced Widget method (Shuttle, 2019). Results indicate discrepancies among methods, with Widget calibrations aligning closer to laboratory data. Using these calibrated parameters, the investigation determines that tailings in the critical structural zone are contractive, posing liquefaction risks under triggering conditions. Stability analyses indicate that the factor of safety in post-peak undrained conditions is below the design target and stabilisation is recommended. Buttress sizing is examined across different methods and liquefied shear strength ratios (Suliq/σ’v). The findings highlight the importance of advanced testing and modeling techniques in evaluating insitu states and their implications for stability assessments and mitigation strategies.
Authors
- Dmitri Bohach, Engineering Intern | SRK Canada
- Bryce Marcotte, Senior Consultant (Civil/Geotech) | SRK Canada
- Erik Ketilson, Principal Geotechnical Engineer | SRK Canada
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