Ford, A, Lucas, DS & Vakili, A 2020, 'Validation of the improved unified constitutive model for open pit applications', in PM Dight (ed.), Slope Stability 2020: Proceedings of the 2020 International Symposium on Slope Stability in Open Pit Mining and Civil Engineering, Australian Centre for Geomechanics, Perth, pp. 953-968, https://doi.org/10.36487/ACG_repo/2025_63
(https://papers.acg.uwa.edu.au/p/2025_63_Vakili/)
Abstract: The improved unified constitutive model (IUCM) was developed by collating the most notable recent research works in the area of rock mechanics and extensive back-analysis of mining case histories together into a unified material model. This model has proven to provide a considerably more reliable prediction of rock mass behaviour than other currently available constitutive models. Comparison between IUCM and other conventional models has been shown by Vakili (2017) and Vakili et al. (2014).
Also, a transparent presentation of the model components and a detailed guideline for the selection of input parameters make the IUCM an excellent candidate to potentially become a standard material model for numerical modelling in rock mechanics.
However, as described by Vakili (2016), the majority of the back-analyses and validation studies completed during the development of the IUCM used mining case histories dealing with small to medium underground excavations including development drives/tunnels, vertical shafts, pillars, and open stopes. Therefore, use of the IUCM for other applications such as open pit slope stability required further verification and validation for open pit case histories.
This paper first provides a brief introduction to the IUCM and then summarises five open pit case studies where the IUCM was used for slope stability analysis. The case studies provide a transparent and unbiased record of not only the successful applications, but also cases where the model was not able to accurately replicate the observed behaviour. These examples provide guidelines on where the IUCM can be used successfully, and where pitfalls may occur.

Keywords: improved unified constitutive modelling (IUCM), advanced numerical modelling, constitutive model, slope stability analysis, case study, back-analysis, calibration, validation