Engineering Rock Mechanics

1 10 Fractures and hemispherical projection

west line 90" and mark and la-

to set 1. Rotate the tick mark 265/42

Extreme values

0 Local minimum

0 Global minimum:4.37

0 Local maximum

Global maximum:89.19

Contour values

EHx I)

D1

80.00

60.00

40.00

20.00

_.__......

__ - - _ _ - _ __

Set normals

+ with set number

3-D variation of RQD for threshold of 0.39 m.

47.7 A rock mass is known to contain two sets of fractures, the
orientations of which are 265/42 and 003/69. What borehole orient-
ations will allow one to drill through the rock mass and intersect all
of the fractures at an angle of 45O (measured between the borehole
axis and the normals to the fractures)? What is the minimum angle
that all fractures can be intersected at?