Models by Jean Biarez for the Behavior of Clean Sands and Remolded Clays at Large Strains - Multiscale Geomechanics: From Soil to Engineering Projects - page 124

Critical void index line

Ic

0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00

p'

0.01 0 .10 1 .00

OCR

100 50 20 10 5 2 1

Figure 5.10. “Relative arrangement of grains”. Abacus -“isotropic stress” for sands and
clays: a) sands: (e max - e min ∼ 0,4) after Mekkaoui 2002; b) clays: (w L ∼ 70%)

5.5. The drained triaxial path for sands and clays

5.5.1. The reference behavior

A certain number of criteria were defined by Biarez for the validation of triaxial
tests [SAI 97] with the goal of obtaining statistics on the normally consolidated
drained behavior of clean sands and clays.

This made it possible for him to establish a set of experimental standards, shown
in Figure 5.11, graduated with the available experimental data ( e pp - e OC and Ψ).

We note the perfect similarity between the NC “black clay” and the “NC sand”.
The black clay is a kaolinite with w L = 70% and M = 0.91. We owe the test to
Zervoyannis [ZER 82]. The “NC sand” is a “wet-poured” sand, i.e. it is very loose
( w = 5%, M = 1.25). We owe this test to Ziani [ZIA 87].

In making these selection criteria, Biarez chose one of the rarely available
drained tests of highly overconsolidated clay without strain localization: the one
performed by Ladd [LAD 64]. Further studies could be developed in this area. The
test selection criteria (“perfect” tests) can be found in Mekkaoui's thesis [MEK 02].