Granular Materials in Civil Engineering: Recent Advances in the Physics of Their Mechanical Behavior and Applications to Engineering Works - Multiscale Geomechanics: From Soil to Engineering Projects - page 70

kept the same or made steeper. The principle of a large enough safety factor (1.5 for
the usual loads) is also to keep strains within a reasonable range. For the same
rockfill embankment, the smaller the safety factor is, the larger the strains will be in
order to mobilize the resisting forces needed to reach equilibrium.
Keeping the example analyzed above, let us consider two corresponding points:
one in the prototype, the other in the extrapolated project (see Figure 3.17). We can
calculate the deformations needed to mobilize the strength required for the static
equilibrium with safety factors of 1.5 for the prototype and 1.1 for the extrapolated
project. From the stress−strain curves measured from large dimension testing on
rockfills of different maximum grain sizes [MAR 69], typical stress−strain curves
can be drawn, including the scale effect on the grain size distribution and the
confining stress influence on the maximum strength and on the strain amplitude at
peak.
Figure 3.17. Scale effects on strains
In our extrapolated project, the coarser material subjected to higher confining
stresses will exhibit a softer mechanical behavior than our prototype, due to a larger
amount of particle breakage.