Truncation Surface
A Truncation Surface can either be drawn within UnWedge, or it can be imported as a DXF file.
To add a Truncation Surface around the perimeter of the tunnel:
- Select: Boundaries > Add Truncation Surface
from one of the 2D views (e.g., Opening Section, Perimeter Support Designer). - Enter the coordinates of the Truncation Surface as described in the Entering Coordinates topic.
Truncation Surface Definition
The Truncation Surface in UnWedge acts as a boundary for Perimeter Wedges. Any Perimeter Wedge extending beyond the Truncation Surface will be truncated.
A truncation surface can also be used as a piezometric line as explained in the Water Pressures topic.
Effects of Truncation on Wedge Geometry
A Perimeter Wedge truncated by the Truncation Surface is no longer tetrahedral in shape. Wedge volume, weight, length, apex height, apex angle, joint area, joint trace length, and joint persistence are affected.
Effects of Truncation on Supports and Other Forces
One of the key advantages of using a Truncation Surface over the Ground Surface is that wedges are truncated while still allowing bolts to pass through. Bolt/Joint intersections may occur either on a joint face or a truncation face on the wedge.
The truncation face(s) of a wedge is not considered as joints. No shear strength, water pressure, or field stresses are applied to these faces.