SWedge Overview

SWedge is a quick, interactive and simple to use analysis tool for evaluating the geometry and stability of surface wedges in rock slopes. Wedges are defined by two (or three) intersecting discontinuity planes, the slope surface and an optional tension crack.

Wedge stability can be assessed using a:

• Deterministic analysis (safety factor),
• Probabilistic analysis (probability of failure), or
• Combinations analysis

In a Deterministic analysis, SWedge computes the Factor of Safety for a wedge of known orientation. In a Probabilistic Analysis, statistical input data can be entered to account for uncertainty in joint orientation and strength values. This results in a safety factor distribution, from which a probability of failure is calculated. In a Combinations analysis, any number of joint planes can be defined, and SWedge will compute all possible combinations of joint intersections that can form a wedge.

Other modelling features in SWedge analysis include:

• Water Pressure on joint planes and/or slope planes
• External and/or Seismic forces
• Active or passive Bolt support
• Shotcrete or Pressure support
• Bench Design option

In all cases, the assumed failure mode of the wedge is translational slip. Rotational slip and toppling are not taken into account.

For a summary and diagrams of typical wedge geometry, see Overview of SWedge Input Data.

For a detailed description of the methods and equations used to calculate the wedge safety factor, see the SWedge Theory Documents.