The Change Slope Angle option is a specialized editing tool which allows you to easily change the overall slope angle of a slope model. You simply choose the toe and crest of the slope, and the change in angle, and all vertices which are connected to the slope will be moved accordingly. This is useful if you want to change the overall slope angle for models with complicated geometry, for example slopes with multiple material layers, or benched slopes. This allows you to easily carry out a sensitivity analysis of the overall slope angle, for slope stability analysis.
To use this option:
Select Change Slope Angle from the Boundaries menu.
You will be prompted to pick a vertex at the toe of the slope. Use the mouse to select the vertex at the toe of the slope on the external boundary. This vertex will be used as the center of rotation for changing the slope angle.
You will be prompted to pick a vertex at the crest of the slope. Use the mouse to select the vertex at the crest of the slope on the external boundary.
NOTE: in steps 2 and 3, you must select a boundary vertex, you cannot choose an intermediate point on the boundary.
You will now see the Change Slope dialog which allows you to enter the angle of rotation, and the method of implementing the rotation. Make your selections in this dialog and select OK, and the overall angle of the slope between the vertices selected in steps 2 and 3 will be updated according to your selections.
The options available in the Change Slope dialog are described below.
Vertex Rotation Type
The Project Horizontally option performs the rotation and ensures that vertices are moved in the horizontal direction only. This is the default option for changing the slope angle.
The Project Vertically option performs the rotation and ensures that vertices are moved in the vertical direction only.
The Rotate option performs a pure rotation of each vertex, so vertices can change position in both the horizontal and vertical directions.
The checkbox Project only the crest of the slope and move each vertex relative to it has the effect of preserving the bench width of individual benches, if your slope consists of multiple benches (e.g. an open pit mine slope). By default this checkbox is turned on. If this option is turned off, then the width of individual benches will change when the overall slope angle is changed.
The Rotation Angle is the desired change in overall slope angle, with respect to the current overall slope angle. You can choose either Clockwise or Counter-Clockwise rotation, to increase or decrease the overall slope angle.
After using the Change Slope Angle option, it is possible that you may still have to edit vertex locations, if some vertices are not in the desired position. This will depend on the complexity of your slope, and whether or not other boundaries (e.g. material boundaries) have also been modified by the change in slope angle.
If your model includes material boundaries which intersect the slope surface, then it is recommended that you start with the MAXIMUM overall slope angle, and use the Change Slope Angle option to REDUCE the slope angle. If you do this, then material boundaries which intersect the slope will simply be cropped at the new slope surface.
If your model includes material boundaries which intersect the slope surface, and you INCREASE the slope angle, the material boundary vertices will get rotated with the slope vertices, and you may need to manually edit the material boundaries after changing the slope angle.
If your model includes support (e.g. bolts) on the slope surface, you will have to manually re-install the support for each new slope angle. Support does not get automatically moved when the slope angle is changed.