From Particle to Material Behavior: the Paths Chartered by Jean Biarez - Multiscale Geomechanics: From Soil to Engineering Projects - page 15

He thus led an active career on both fronts, as an academic researcher and as an
engineering expert.
This chapter describes and analyzes Jean Biarez's contribution to the scientific
domain. The first thing to note is that from early on he demonstrated that a realistic
modeling of soil behavior could only come from a better understanding of the
phenomenon taking place at the local scale, i.e. at the scale of the grain. If we
consider his contribution on the international level, he was one of the first people in
soil mechanics to identify, analyze and grasp the relevant mechanisms at the local
scale that could lead to a better understanding of the “representative elementary
volume” (REV). This subject was explored in his own PhD thesis [BIA 62], and
later developed in the various PhD theses written under his direction [CAM 72,
WIE 64].
During the time that he was engaged in essentially fundamental research, Jean
Biarez was also trying to devise usable solutions for designing rockfill dams. Let us
remember that in the years between the 1950s and 1960s, many dams were built in
France and all over the world. One of the major civil engineering challenges was to
come up with designs that could relate the calculations between the behavior of the
blocks to that of the engineering project. At that moment in time it was impossible to
characterize the behavior of these materials at the “representative elementary
volume” scale because the size of the materials was not compatible with the test
devices of the day. Analyzing the material at the local level, according to Biarez,
could create some practical rules for the art of civil engineering. Here we encounter
the chain of reasoning that guided nearly all the research projects he initiated: how
to analyze in order to better understand, better model and better design. This process
started from relatively fundamental research and resulted in providing the engineer
with a proper design tool. This continual exchange between science and engineering,
a source of creativity for both researchers and engineers, is an important
characteristic of Jean Biarez's professional activity. We will therefore discuss his
scale change approach and the fundamental and operational objectives that he
explored from his earliest days.
2.2. The available tools, the variables analyzed and limits of the proposed
analyses
At the time of writing his PhD thesis, the tools available to researchers were very
limited. Some experimental tests were performed on real materials in the case of
analyzing grain breakage, for example. As for performing other analyses, such as
local anisotropy, it was very difficult to manipulate three-dimensional materials.
This was the reason why Jean Biarez and some of his PhD students [BIA 63,
CAM 72, WIE 64] developed and analyzed tests on analogical two-dimensional