Waste Rock Behavior at High Pressures: Dimensioning High Waste Rock Dumps - Multiscale Geomechanics: From Soil to Engineering Projects - page 102

These results were also plotted in Figure 4.16 and show the suggested evolution
of dry density with the effective mean stress p', deduced from the vertical stress
applied σ' v , associated with the equivalent overburden height of the dump. The
values plotted correspond to the dry densities obtained at the end of the tests or from
each loading step. The results obtained from drained compressional triaxial tests
reaching effective mean stresses higher than p' = 5 MPa, roughly equivalent to a
vertical stress of σ' v = 8.5 MPa, are also included in this figure. It is important to
mention that for the results of the compressional triaxial tests, the dump height is
correlated with the final mean stress of the test.

Effective Mean Stress, p' (x 0.1 MPa)

Drydensityevolution
ROMWR,homothetic GSD,triaxialtest
LeachedWR, homotheticGSD, triaxialtest
LeachedWR, GSD <8", triaxial test
CrushedWR,triaxialtest
LeachedWR, oedometrictest
LeachedWR, oedometrictest
LeachedWR, oedometrictest
ROM WR,oedometric test
ROMWR,oedometric test
ROMWR,oedometric test
Drydensityevolutionproposed

0 10 2 0 3 0 4 0 5 0 6 0

2.5

0.1

2.4

0.2

2.3

2.2

0.3

2.1

2.0

0.4

Dry density evolution adopted for a
specific design of high WRD

1.9

0.5

1.8

1.7

0 40 80 120 160 200 240 280 320 360 400 440 480 520 560 600
Waste Rock Dump Height (m)

Figure 4.16. Evolution of the dry density with waste rock dump height, estimated from
oedometric and compressional triaxial tests results [ARC 06-07]

4.6. Stability analysis and design considerations

High waste rock dumps are structures presenting major challenges and their
construction procedures need to be improved by adopting a number of pre-emptive
measures to reduce potential instabilities.

The dump design must be consistent with the stability criteria adopted. In steep
valleys, it is necessary to consider dump lifts of a certain height that are compatible
with the pit benching height and truck operations. This is necessary in order to
reduce the height of the advancing face and excessive segregation of the waste, two
conditions that lead to potential instabilities. The design criteria should also be in
accordance with the closure plan, to avoid a large and almost impracticable waste