Civil Engineering Reference
In-Depth Information
N
Fisher
concentrations
% of total per 1.0% area
(a)
0-2%
2-4%
4-6%
6-8%
8-10%
10-12%
12-14%
14-16%
16-18%
18-20%
W
E
No bias correction
Max. conc. = 16.6262%
Equal area
Lower hemisphere
123 poles
124 entries
S
N
(b)
Sheet
joint
Orientations
ID
Dip/Direction
Face
J
2
56/284
25/294
90/184
73/095
80/270
Sheet jt.
J
4
J
3
W
E
J
4
=36
°
Face
Equal area
Lower hemisphere
J
3
Figure 14.8
Stereonets of
structural geology of slope in
Case Study II: (a) contoured plot
showing pole concentrations;
(b) great circles of joint sets, slope
face and friction circle.
J
2
S
had already taken place along the
in situ
sheet
joints, it was considered appropriate to use the
residual friction angle in design.
Careful examination of the rock along the
sheared sheet joints showed that the rock was
crushed and there was little intact rock contact.
Therefore it was decided that it would not be
appropriate to include a roughness component to
friction angle, and a friction angle of 36
◦
used in
design.
14.3.4 Ground water
The site was located in an area with high precipit-
ation in the form of both rain and snow. Although
there were no piezometers to measure water pres-
sure in the slope, the level of the water table was
assessed from observations of seepage from sheet
joint exposed at the base of the lowest block. It
was expected that the water table would generally
be low because of the dilated nature of the rock
