Compression and swelling - The Mechanics of Soils and Foundations - page 111

Figure 8.7 States of soils on the wet side and on the dry side of critical.

nature of the soil; most soils will be lightly overconsolidated at R p < 2 and heavily

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overconsolidated at R p 3.

Sands and gravels may be loose or dense depending on the position of the state with
respect to the critical overconsolidation line, as shown in Fig. 8.7(b). Notice that the
state is defined by a combination of specific volume and pressure. In Fig. 8.7(b) the state
at A is dense while the state at B is loose although the specific volume at B is smaller
than at A: this is because the stress at B is considerably greater than at A. Similarly,
in Fig. 8.7(a) the state at A is heavily overconsolidated while the state at B is only
lightly overconsolidated although the specific volume at B is smaller than that at A.
The regions in which clays are normally consolidated or lightly overconsolidated and
sands that are loose are said to be on the wet side of the critical line, as shown in
Fig. 8.7(c), and the regions where clays are heavily overconsolidated and sands are
dense are said to be on the dry side. We will find later that there are fundamental
differences in the behaviour of soils when they are sheared from states initially on the
wet side or initially on the dry side of the critical line.
Do not misunderstand the terms wet side and dry side. The soil is always either
saturated or dry and it is simply that at a given stress, such as p c in Fig. 8.7(c), the
specific volume (or water content) on the wet side is higher than v c (i.e. the soil is