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and his unflinching physical and experimental approach concerning their
assemblage that led him to pronounce this sort of sweeping generalization.
His particular vision of grain assembly led him to conceive a system of logic that
could subsequently connect the parameters of all soils. Considering grains as many
continuous media (the properties of grains) with their boundary conditions in space
(the assembly) and in stresses (the confinement), he deduced that the properties of
soils (the deformability and rupture parameters of the imaginary “continuous
medium”) were indeed the combined substance of the mechanical properties of these
multiple continuous media, or real “discontinuous medium”, with different boundary
conditions. He created the parameters for “nature of grains” and the “arrangement
and confinement of grains” in order to explain the “mechanical parameters of soils”.
His system of reasoning, which has been adopted by those who followed him in the
quest to resolve mechanical continuous media problems, coupled with an
experimental and physical reasoning, is at work in all of his models. This approach
is particularly evident in the confrontation between his oedometric modeling and
Burland's modeling; indeed, as we have emphasized, the parameters e*
100
and e*
1000
are simply the parameters of “nature of grains”, as the response of the grains (as
w
L
and
w
P
) to a particular loading.
We should point out that Biarez's approach was basically experimental and
physical, and that he left to others the task of quantifying and digitalizing all the
elements that for him were only reference points, reference standards and graphs
within the system of axes; all these elements had enormous pedagogical value for
understanding granular media behavior.
Nevertheless, Biarez was no stranger to numerical work. Towards the end of the
1960s, he himself promoted parameter correlation statistical analyses which, thanks
to the emerging models, helped to create a safety approach. This approach aimed to
ensure the safety of earthwork constructions by considering all the uncertain
elements that still clouded the engineer's knowledge about the real behavior of
granular materials. A real behavior could be compared to a modeled standard
reference behavior, from which it would be possible to appreciate the errors and
uncertainties contained in the measured parameter values. By taking into account all
these elements of uncertainty, academics could propose a global safety approach to
earthwork calculations [FAV 95]. Before these scientific developments, it was not
possible to treat the uncertain elements confronting real earthwork behavior from the
outset, simply because the uncertainties were part and parcel of the predictions of
the model. Given the fact that the sources of uncertainties could be distinguished
from the beginning, it has become possible to assess their relative importance more
efficiently.
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