Since 1990s, researchers in the discontinuous deformation analysis (DDA) community have dedicated a great deal of effort on the stability analysis of slopes, tunnels and caverns. This paper contains a summary of more than 80 published papers or theses concerning stability analysis using DDA. These studies are grouped into the following two categories:
validations with respect to analytical solutions, laboratory experiment results or field data; and
applications of rock stability analysis using DDA.
After reviewing the validations and variety applications, we are focusing on discussing recent issue in this research filed: limitations and solutions concerning cohesive-friction in DDA stability analysis. Addressed by this review, we find that DDA can perform more than adequately in stability analysis for a variety of engineering problems. In addition, we present a general solution for modeling rock masses behaviors with cohesive-friction joints.
Stability analysis of rock masses is important in rock slope and tunnel engineering, open pit and underground mining excavation in general. The term stability of rock masses may be defined as the resistance of rock masses to failure by sliding, toppling or collapsing as an extension of the rock slope stability (Kliche, 1999). The main objectives of stability analysis for rock masses are finding endangered areas, investigation of potential failure mechanisms, determination of the sensitivity to different triggering mechanisms, and designing of countermeasures with regard to safety, reliability and economics, e.g. cutting and filling; anchoring; walls and resisting structures (Eberhardt, 2003).
In geotechnical practice, limit equilibrium methods (LEM) and finite element methods (FEM) are widely used for routine stability analyses. LEM has the advantage of simplicity, and provides a simple index of relative stability in the form of the factor of safety. FEM provides more information about the actual stress that may occur, allowing more refined estimates of stability.
In general, most rock masses are discontinuous by joints over a wide range of scales, from macroscopic to microscopic. The intersection of joints forms the so-called "block" masses. Therefore, it has been long appreciated that the rock masses behavior is significantly influenced by the contained discontinuities. LEM and FEM may be sufficient for the rock masses that could be approximated by a continuous medium, which are comprised of massive intact rocks, weak rocks, or heavily fractured rock masses. However, they meet their applicable limitations according to their underlying assumptions when the behavior of rock masses is controlled by the geometry of discontinuities such as fractures, joints or faults.