ABSTRACT
Detailed information on the spatial variation of rock mass geomechanical properties is essential for pit slope design. This information can be used for an optimized slope design, and for more accurate identification of the high-risk zones (low quality rock mass zones) along the pit walls. Geostatistical techniques have been successfully used for modelling the spatial variability of rock mass geomechanical properties. The 3D geotechnical block models that are developed using the geostatistical techniques could model both the randomness and spatial structures of a geomechanical variable. Thus, the heterogeneity and anisotropy of geotechnical properties can be modelled. This paper presents the results of a geostatistical simulation method used to develop a 3D geotechnical block model of Rock Mass Rating (RMR) for an open pit iron ore mine in Canada. Geotechnical data from boreholes was used for the spatial modelling of the geomechanical attribute. Five realizations of the RMR block models were generated. The resulting 3D block models of RMR were used to track geotechnical risks in different pit configurations throughout the life of mine. The probability of weak/very weak rock mass blocks (RMR < 40) intersecting the pit walls at different years, during the life of mine, were calculated. This allows development of a risk-time graph that can help mine design engineers to better understand the potential of slope failure in different years, during the life of mine and to make appropriate plans for mitigating these risks.
