Abstract
The rock mass properties significantly impact the rock slope design, especially for the fractured and heavily jointed conditions. The traditional continuum finite element method (FEM) approaches use the intact rock properties with some reduction by using rock mass classification systems such as the Geological Strength Index and design the slope based on the critical strength reduction factors. A limitation of this approach is that the reduction of the rock mass properties might not be accurate enough for the rock slopes with heavily jointed rock mass. This study uses a three-dimensional Discrete Fracture Network (DFN) approach to understand the inherent limitations of continuum methods in capturing discontinuous rock slope failure with increasing fracture density. The fracture network was constructed from the field data of an iron ore mine comprising detailed face mappings of 560 joints in both the host rock and the iron ore, while the intact rock properties were derived from core samples obtained through 98 boreholes. Comparative analysis across fracture intensities revealed that the conventional FEM-based methods substantially underestimate the influence of joint volume, yielding higher factors of safety than the DFN approach, highlighting the importance of incorporating DFN models over continuum-based approaches, particularly under increasing fracture density.
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