Authors: Elmo, D; Yan, M; Stead, D; Rogers, SF

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Elmo, D, Yan, M, Stead, D & Rogers, SF 2007, 'The Importance of Intact Rock Bridges in the Stability of High Rock Slopes - Towards a Quantitative Investigation Using an Integrated Numerical Modelling;Discrete Fracture Network Approach', in Y Potvin (ed.), Proceedings of the 2007 International Symposium on Rock Slope Stability in Open Pit Mining and Civil Engineering, Australian Centre for Geomechanics, Perth, pp. 253-266.

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As large open pit rock slopes reach increasingly greater depths and more frequently involve interaction with underground mines the need to consider intact rock fracture becomes ever more important. This paper emphasizes the importance of brittle rock failure propagation through intact rock bridges in high rock slopes, with reference to both large open pits and their natural analogues, high mountain slopes. Quantification of discontinuity persistence and intact rock bridges within rock slopes is a critical component of rock slope research and requires not only the use of new data collection techniques but also data interpretation through rigorous fracture network analysis. Using probability density functions to represent discontinuity orientation, spacing and persistence, the Discrete Fracture Network (DFN) approach is shown to represent an ideal numerical tool with which to synthesise realistic fracture network models from digitally and conventionally mapped data. Integration of a DFN model with a hybrid geomechanics code that is able to model fracture propagation allows the simulation of the interaction between naturally occurring discontinuities and brittle fracture through intact rock bridges. Having discussed the applications and limitations of a 2-D discrete numerical approach, simulations are presented based on DFN models of a large conceptual rock slope and incorporating varied failure mechanisms. Simulations demonstrate the importance of considering both realistic fracture mechanisms and the ability to model complex failure paths involving sliding along discontinuities, dilation, and intact rock fracture. The paper concludes with a discussion on the definition of intact rock bridges for a 3-D analysis. Significant future challenges presented by the incorporation of inherently 3-D rock structures in large-scale numerical models are emphasised.

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The Importance of Intact Rock Bridges in the Stability of High Rock Slopes ― Towards a
Quantitative Investigation Using an Integrated Numerical Modelling; Discrete Fracture Network Approach D. Elmo, et al.
266 Slope Stability 2007, Perth, Australia

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