Environmental Engineering Reference
In-Depth Information
Set A structures
Set B structures
N
Highest concentration
of intersections
10
°
N 55
W
°
20
°
30
°
40
°
50
°
S
FIGURE 6.14
Example of Wulff stereo-net showing relationship of two joint sets on the south slope of an open-pit mine. The
greatest concentration of joints in set
A
dips at about 45ºE and strike N55º; therefore, a cut slope made at this
orientation or greater would be essentially unstable since the cut slope would intersect the dip. (From
Seegmiller, B. L.,
Proceedings of ASCE, 13th Symposium on Rock Mechanics,
University of Illinois, Urbana, 1972,
pp. 511 - 536. With permission.)
(Figure 6.21).
The resistant sandstones form vertical slopes and the softer interbedded sand-
stones and shales; and shales form slopes with relatively gentler inclinations.
Limestone
Formations
The most significant features of pure limestone result from its solubility in water. Impure
limestones usually take the forms of other sedimentary rocks during decomposition.
Solution results in cavities, providing the mass with an irregular rock surface, large and
small openings within the mass, and distinct surface expressions (see also
Section 10.4.2).
