External Force
External Forces (e.g. a structural load on the upper surface of a slope, or the force applied by a waste rock berm to the toe of a slope) can be applied to the sliding block, with the External Forces option in the Input Data dialog.
To include External Forces in the analysis:
- Select the Number of External Forces.
- Enter the Angle (of inclination) and Magnitude of each force.
- Select the Apply button to run the analysis.
How External Forces are Implemented
In the RocPlane analysis, an External Force is exactly equivalent to a rock bolt, using the ACTIVE bolt model. This means that an External Force with the same orientation as a rock bolt, and with a Magnitude equal to the Capacity of the rock bolt, will have exactly the same effect on the Safety Factor, if the bolt model is ACTIVE. See the How Bolts are Implemented topic for more information.
Display of External Forces
If External Forces have been applied to a model, the Forces will be represented on the model, as purple arrows at the center of the wedge face. These arrows are symbolic and indicate the direction and existence of External Forces. They DO NOT indicate the magnitude of the forces. The display of these arrows can be turned on or off, and the default arrow colour can be changed, in the Display Options dialog.
Note that the location of the External Force display does NOT indicate the actual location of the forces applied in the analysis. As with all other forces in RocPlane, External Forces are applied through the centroid of the wedge, during the analysis.