Page 209 - Analysis and Design of Energy Geostructures

182 Analysis and Design of Energy Geostructures

Figure 4.24 Representation of the achievement of the critical state with reference to the behaviour
of soils: evolution of axial strain with (A) deviatoric stress, (B) volumetric strain and (C) void ratio.

shear strength compared to the maximum strength manifested under a dense or over-
consolidated state. This aspect is shown in Fig. 4.25, considering values of cohesion
and angle of shear strength in the Mohr plane, τ 2 σ n (where τ is the shear stress and
σ n is the normal stress), for a dense or overconsolidated material, in correspondence of
the maximum shear stress (at the peak) and at critical state (under constant volume
conditions). In the former case, the values of the considered variables are typically
termed peak cohesion, c, and peak angle of shear strength, ϕ. In the latter case, refer-
ence is made to cohesion and angle of shear strength under constant volume condi-
tions, c cv and ϕ , respectively.
cv