Probabilistic Stability Assessment Of Key Blocks In Jointed Rock Excavation

Uncertainty and variability are inevitable in geotechnical engineering researches relating tonatural rock materials. The deterministic analysis method, based on fixed values of discontinuityparameters and the factor of safety concept, is not proper to handle these problems. Thus, theprobabilistic analysis method, as an alternative approach, has been introduced to the geotechnicalengineering area. The assessment of the proposed method will be applied to data from HillgroveResources’s Kanmantoo project in the Adelaide hills in Australia. Based on the analysed data ofgeometrical and mechanical parameters of fractures from the site, the rock mass will be modeled,and attempts will be made to identify wedge formations within this model with using a computerprogram. Once wedge forming structures have been identified, the properties and occurrence ofthese wedges will be analysed in the next stage. And then the impacts of mechanical parameters offracture on the stability of wedges will be discussed. Finally, an assessment model of wedgefailure probability based on the reliability theory will be established, and in the calculation therandom properties of the geometrical and mechanical parameters of discontinuity are taken intoaccount simultaneously. To evaluate the feasibility of the new method, the method was applied toanalyse some wedges. Results show that the probabilistic approach can be used effectively toassess the rock wedge stability with random properties of discontinuity parameters.