Environmental Engineering Reference
In-Depth Information
80
Approximate location of bounds from
Indraratna et al. (1993)
70
60
50
40
30
20
10
40
70
100
400
700 1000
4000
7000
Sigma n (kPa)
Figure 6.37.
Variation of secant friction angle
sec
with normal stress
n
(Douglas, 2003).
sec
with normal stress
n
for dense
Figure 6.37 shows the variation of secant friction angle
rockfill. The strong dependence of
sec
.
Douglas (2003) carried out non-linear statistical anlaysis on the database. The estima-
tion method used was least squares. An analysis of the form shown below was found to
be the most effective for relating
sec
on
n
is evident, as is the wide variation in
sec
to
n
.
sec
ab
n
c
(6.29)
′
′
The analysis resulted in the following constants:
a
36.43
0.267ANG
0.172FINES
0.756(c
2)
0.0
459(UCS
150)
(6.30)
c
b . 110.27ANG
0.549FINES
5.105(c
2)
c
0.4
08(UCS
150)
0.408
(6.31)
c
. 4
(6.32)
where ANG
5.5; otherwise 0. rounded
particles have an angularity rating of 0, crushed angular rock a rating of 8. The rating is
subjective (Douglas, 2003).
(angularity rating
5) for angularity rating
(6.30a)
FINES
percentage of fines passing 0.075 mm (%).
3
2
d
dd
c
c efficient ofcurvature
(6.30b)
c
10
60
