In order to enable the Terzaghi weighting option, traverses must be defined in the Traverse information dialog. When at least one traverse has been defined, a traverse column will appear in the Dips spreadsheet. The traverse column is used to enter the Traverse ID number for each measurement.
In the Traverse Information dialog, the traverse orientation format is as follows:
- For a Planar Traverse, Orient1/Orient2 corresponds to the planar orientation of the measurement surface (e.g. tunnel wall orientation). The format must correspond to the Global Orientation Format selected in Job Control (i.e. Dip/Dip Direction or Strike/Dip). For example, for a vertical wall running north/south, if your Global Orientation Format = Strike/Dip then Orient 1 = 0 and Orient 2 = 90.
- For a Linear Traverse, Orient1/Orient2 always correspond to the Trend/Plunge of the scanline (regardless of the Global Orientation Format). For the same example as above, a linear scanline along the tunnel wall would give Orient 1 = 0 and Orient 2 = 0.
Once the traverses are defined in the Traverse Information dialog, then you must enter the Traverse ID number for each measurement in the Traverse column in the main Dips spreadsheet.
The Minimum Bias correction angle serves to limit the maximum Terzaghi weighting factor. The value of 15 degrees is somewhat arbitrary, and not critical to the results of the analysis. It simply means that any planes which intersect a traverse orientation at an angle LESS THAN the minimum bias angle will be limited to the weighting factor corresponding to the minimum bias angle. Without this limit, the weighting factor for a plane which is nearly parallel to the traverse orientation tends to infinity.