Models by Jean Biarez for the Behavior of Clean Sands and Remolded Clays at Large Strains - Multiscale Geomechanics: From Soil to Engineering Projects - page 115

The “arrangement of grains”, therefore, appears to be directly linked to the
consolidation stress tensor through the mineralogical properties. This connection
corresponds, in the ( I L - σ' v ) plane, to a straight line called NCRS (normally
consolidated remolded simplified, see Figure 5.3). Thus, a normally consolidated
remolded clay will be represented by points located on the NCRS and the
overconsolidated remolded clay by points below the NCRS. In this case, the
overconsolidation of the material only depends on the clay loading history,
expressed by the overconsolidation ratio (OCR) = σ' p /σ' v . Here σ' p is the maximum
effective stress and σ' v is the overburden effective stress.
Figure 5.3. Clayey soils behavior in (I L - σ ' v ) plane
For the natural deepwater GoG (Gulf of Guinea) marine clay, which will be
examined below in the Biarez and Burland models, the liquidity indexes calculated
at different depths (then, at different overburden stresses) as shown in Figure 5.3,
give a cloud of points located above the NCRS line. Greater porosity than that
predicted by the NCRS for an equivalent stress σ' v , characterizes this material.
Thus, the sediment can be defined, in a first approximation, as a clay constituted of
“grains” linked by a physicochemical cementation [FAV 06, HAT 10]. Aggregates
seem to have a very complex structure, as seen in Figure 5.4, which shows an
organo-mineral aggregate composed of a “foliage” of smectite particles, where some
spheroids of framboïdal pyrite are bonded. We could ask whether there is a possible
phenomenological analogy between these highly porous deep-water marine
sediments and the sandy lumps with dual porosity (inter- and intra-lumps), which
remain very loose due to capillary cementation (see section 5.8 and Figure 5.16).