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As large open pit rock slopes reach increasingly greater depths and more frequently involve interaction with
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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
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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