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q(x0.1MPa)
q(x0.1MPa)
70
70
60
60
50
50
40
40
30
30
20
20
Leached
Waste Rock
10
10
0
0
0
5
10
15
20
1 (%)
0 10203040506070
p' (x 0.1 MPa)
0.5 e
v (%)
U (0.1 MPa)
25
-2
20
0.4
-4
15
0.3
-6
10
0.2
-8
5
-10
0
0.1
0
5
10
15
20
1 (%)
0 10203040506070
p' (x 0.1 MPa)
Figure 4.9. CID and CIU triaxial tests on leached waste rock,
cut grain size distribution [BAR 07b]
It is interesting to note that the undrained strength obtained on these materials
(C u /σ' 30 =0.28-0.29) is similar to the results obtained on the fine matrix of leached
copper waste dump material [VAL 04] , presented in Figure 4.10.
4.4.4.3. Shear strength envelopes
Figure 4.11 shows the shear strength envelopes, deduced from the tests
performed, plotted in the Mohr plane [τ, σ' n ], in addition to those reported in the
technical literature for coarse granular materials coming from hard rocks [MAR 75] .
As observed in this figure, the results obtained from the waste rocks agree rather
well with the shear strength envelopes, suggested for other granular materials,
especially in the range of pressures below σ' n = 2 MPa.
At higher levels of stress, the strength envelopes start to curve due to the greater
compressibility of the granular matrix associated with the crushing of particles
[BIA 92].
 
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