Evaluation significance of differences between the geotechnical parameters of the lithological rocks roof layers, above mining excavation

The article presents the results of the analysis data of the roof rocks geotechnical parameters in the conditions of the deep copper ore of the KGHM Polish Cooper mines. Using single factor analysis of variance and comparing means in two samples, the significance of differences between individual lithological layers (dolomite, anhydrite and rocks on their contact (dolomite-anhydrite breccia)) was evaluated in the aspect of constructing numerical simulations of the behavior of roof rocks above mining excavations. Based on the results of previous studies described in the works (Galiński 2005; Galiński, Lis and Mróz 2003), it was proposed to use Fisher–Snedecor analysis and t-Student test in order to justify the decision to consider individual lithological layers in numerical modeling of the rock mass around mining excavations. The problem raised in the article concerns the selection of lithological layers consider in numerical models of rock mass. Assuming too general (average values) physico-mechanical parameters in the simulation will generate incorrect results. On the other hand, consider of more lithological layers with insignificantly different physico-mechanical parameters may prove unnecessary, because this will not affect the accuracy of the results obtained.