ABSTRACT:
A modelling approach for rock slopes is proposed that is based on discrete element formulation. This model allows damage to occur and propagate within intact rock blocks and along discontinuous joint sets. The model uses traditional shear strength failure criteria and joint stiffness parameters. The discrete element modelling methodology has been applied to direct shear box test results and several rock slopes to examine the capabilities of this modeling approach. The role of tensile strength on slope instability has been investigated and proved to be important when confining stress conditions are low such as in toppling slope failure.
1 INTRODUCTION
Analysis of a rock slope typically requires an evaluation of the rock structure, an assessment of the mode of failure and the strength of the material. Once a critical failure mode is determined, both continuum or discontinuum analyses can be readily applied and the analyses are relatively straight foreword. However, in many rock slope situations no obvious failure mode or surface of rupture are evident and in such situations continuum and in many cases discontinuum analyses are not appropriate. Eberhardt et al. (2004) showed that a continuum/ discontinuum hybrid approach based on fracture mechanics could be used to simulate slope failure in massive brittle rocks. However most rock masses in nature have discontinuities and for those situations a discontinuum approach that can readily accommodate discrete fractures as well as provide for the growth of new fractures is desirable. Wang et al. (2003) used discrete elements to analyze a jointed rock slope by bonding circular disks. However, it is not clear how spheres should be calibrated to represent discontinuities as the spheres create very irregular surfaces. Potyondy and Cundal (2004) noted that using bonded particles to represent intact rock required extensive calibration.
