Ayala, J, Fourie, AB, Reid, D & Jefferies, M 2024, 'Inferring the state parameter from partially drained cone penetration test data using the soil behaviour-type index to adjust drained/undrained correlations ', in AB Fourie & D Reid (eds), Paste 2024: Proceedings of the 26th International Conference on Paste, Thickened and Filtered Tailings, Australian Centre for Geomechanics, Perth, pp. 335-348, https://doi.org/10.36487/ACG_repo/2455_27
(https://papers.acg.uwa.edu.au/p/2455_27_Ayala/)
Abstract: Estimating the in situ state parameter (ψ) of mine tailings is crucial when evaluating susceptibility to liquefaction. This is usually done from cone penetration test (CPT) data. However, CPTs in partially drained conditions, which are common in mine tailings, do not have an established methodology of interpretation as yet. A simplification of the characteristic surface approach is developed to provide a method for estimating ψ which can be easily implemented in a spreadsheet. This simplified method avoids enforced use of state estimates based on fully drained or undrained CPT correlations, which can lead to incorrect dilative or contractive material state characterisations.
This simplified version of the characteristic surface method is based on using the soil behaviour-type index to infer the drainage conditions, allowing inference of ψ continuously from fully drained to fully undrained CPT responses. This approach improves the understanding of the differing effects of state and drainage over the CPT record.

Keywords: cone penetration test, partial drainage, state parameter, soil behaviour-type index, characteristic surface