Site Investigation - Rock Mechanics Based on an Anisotropic Jointed Rock Model - page 390

Figure 13.29 Transformation of and if the horizontal orientation appears (Wittke 1990)

α β

If a set includes vertical orientations, the range of dip values is extended to 0° ≤ ≤ 180°

and α and β must be transformed in the following way (Wittke 1990):

(13.12)

(13.13)

The angle α 0 depends on the strike direction of approximately vertical dipping disconti-

nuities and is introduced in order to distinguish between steeply sloping discontinuities
that dip in opposite directions. According to Fig. 13.30, the orientations of discontinuities
whose poles are located in the yellow colored area of the pole plot are to be described by
= α - α 0 and = β and those whose poles are located in the green colored area are

to be described by = α - α 0 - 180° and = 180° - β .