Bahrani, N, Sanipour, S & Hamediazad, F 2024, 'The strength of massive to moderately jointed hard rock masses for tunnel and pillar designs', in P Andrieux & D Cumming-Potvin (eds), Deep Mining 2024: Proceedings of the 10th International Conference on Deep and High Stress Mining, Australian Centre for Geomechanics, Perth, pp. 1123-1134, https://doi.org/10.36487/ACG_repo/2465_73
(https://papers.acg.uwa.edu.au/p/2465_73_Bahrani/)
Abstract: This paper presents the results of a series of numerical studies conducted to simulate the damage process and failure of hard rock masses and to estimate their strength for the design of underground excavations. In these studies, the numerical models were calibrated against an empirical brittle failure criterion, commonly known as the S-shaped criterion, in order to replicate the damage evolution leading to the failure of massive to moderately jointed hard rock masses. It is demonstrated that the models calibrated to rock mass strength using the S-shaped criterion realistically replicate the failure around a test tunnel and within slender pillars under compressive and shear loading conditions. However, they tend to overestimate the strength of wide pillars compared to the empirical pillar strength database. When calibrated against the strength of pillars from the database, the models significantly underestimate the confined rock mass strength compared to the S-shaped criterion and the GSI-based Hoek–Brown failure criterion. 

Keywords: rock mass strength, brittle failure, tunnel design, pillar design, S-shaped failure envelope