Seismic Force
Seismic Force can be applied to the wedge by selecting the Seismic check box in the Input Data dialog, and entering the following data:
Seismic Coefficient
The seismic coefficient is a dimensionless number that defines the seismic acceleration as a fraction of the acceleration due to gravity. Typically the Seismic Coefficient might be around 0.1 to 0.2.
If a = Seismic Coefficient, g = acceleration due to gravity = 9.81 m/s2, and m = mass of the sliding block, then the Seismic Force applied to the block, F = a m g.
Direction
- By default the Seismic Force will be applied to the wedge in the HORIZONTAL direction.
- However, the user may define the Seismic force at any angle from the horizontal, by selecting the USER DEFINED option for Direction, and entering an Angle.
Display of Seismic Force
If Seismic Force has been applied to a model, the Force will be represented on the model as a yellow arrow at the lowermost wedge vertex on the slope face. The arrow is symbolic and indicates the direction and existence of a Seismic Force. It does NOT indicate the magnitude of the force. The display of this arrow 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 Seismic Force display does NOT indicate the actual location of the force applied in the analysis. As with all other forces in RocPlane, a Seismic Force is applied through the centroid of the wedge, during the analysis.