Run a Wedge Stability Analysis

To run a wedge stability analysis, you need at least two orientation sets containing discontinuities that may intersect to form at least one wedge. See Create Orientation Sets.

The Stability Analysis button is only available when an option in the Analysis section of the Project Tree is selected.

Activity Steps

  1. Open the Analysis menu.
  2. Select Stability Analysis in the Analysis menu group.

    The Stability Analysis Wizard displays.

  3. Click Next.
  4. Select Tetrahedral Wedge Analysis.
  5. Click Next.
  6. Select the orientation sets to use from the two drop-down menus at the top of the Select Orientation Sets section.
  7. Configure the following fields as required.

    Note: All options may not be available in your orientation sets.

    • Cohesion – Component of shear strength of a rock that is independent of interparticle friction. Units: kPa.
    • Friction – Angle of internal friction. The ability of the rock to withstand shear stress. Units: degrees.
    • Persistence – Persistence of a discontinuity. The diameter of the idealised disc representing the discontinuity. The persistence value used is dependent on the selected Persistence Method.
    • Persistence Method – Persistence applied to discontinuities of a set. Select from the following options.
      • Mean – Use the mean persistence of the set.
      • Maximum – Use the maximum persistence of the set.
      • Custom – Manually input the value.
      • Local – Use the persistence of each discontinuity).
    • Factor of Safety Threshold – Factor of safety cut-off for unstable wedges.

  8. Click Next.

    Note: The computation of the existence of wedges considers the geometry of each pair of discontinuities and tests to see if they both intersect and daylight on the rock face. Once a potential wedge has been identified, the domain characteristics of the rock surface, such as pore pressure and cohesion, are used to determine the wedge’s factor of safety using limiting equilibrium analysis. Finally, characteristics of the wedge are calculated, such as its mass and volume.

  9. Click Next.
  10. Click Finish.