Over-excavation in underground opening is one of the most significant geo-mechanical hazards in mining and civil projects with potential consequences including cost overruns, time delays, increased rehabilitation, grade dilution, equipment damages, injuries, loss of human lives, and social or environmental consequences. The main objective of this study is to detail study the role of non-controllable parameters, namely rock type, geometrical, topological, kinematical and geo-mechanical properties of the discontinuity network, and in-situ stress on over-excavation around a tunnel of El Teniente Mine. To this end, we investigate the role of each of these parameters on the over-excavation around tunnel using cause–effect approach. We performed extensive sensitivity analysis using Monte Carlo simulation techniques of discrete fracture network and carry out the rigid block failure analysis to capture contribution of the non-controllable parameters on the kinematic state of the rock blocks. It is worth to mention that we assume that the constant value of in-situ stress around tunnel due to low coefficient of variation of the in-situ stress around tunnel (less than 5%). The rock type does not show a significant impact on the over-excavation. The mutual interaction between the induced stress around tunnel and discontinuities shows a significant correlation with observed over-excavation around tunnel. We used the microseismic data to study the potential correlation between over-excavation, fracturing process, and the non-controllable factors. According to the results of this study, the pre-existing discontinuities and their mutual interaction with induced stress around tunnel are the key factors on variational trend of the over-excavation along tunnel at El Teniente mine.