Parametric Studies on the Behaviour of Reinforced Soil Retaining

The failure mechanisms of both extensible and inextensible reinforcement have been
studied. Their failure mechanism is shown in Figure 2.5.
(a) Series Failure (inextensible reinforcement) (b) Parallel Failure (extensible
reinforcement)
Figure 2.7: Analogy of Reinforced Soil Failure Mechanisms (Jones, 1985)
2.4 Concept and Mechanism of Reinforced Soils
Several experimental and theoretical investigations have been performed since the
invention of Reinforced Earth wall (Vidal, 1963) to understand the concepts and
mechanism of reinforced soil structure and interaction among its basic components,
reinforcing elements, backfill soil and facing. H. Vidal, the pioneer of Reinforced
Earth systems seems to be the first person to propose a general and realistic concept
of reinforcing a soil.
Anisotropic Cohesion Concept
Schlosser and Long (1972) indicated that the reinforced soil has higher shear strength
than unreinforced plain samples (Fig. 2.6). Haussmann (1976) independently
postulated a more unified anisotropic cohesion theory. They have shown that two
failure modes can develop in such reinforced sand samples:
(a) Failure by slippage of the reinforcement at low confining pressure leading to a
curved yield line passing through the origin and
(b) Failure by reinforcement breakage at higher confining pressure leading to a
straight failure line which proves that the reinforced sand behaves as a cohesive
material having the same frictional angle as the original sand and an anisotropic
pseudo-cohesion due to reinforcements as shown in Fig. 2.8. This pseudo-cohesion is
very rapidly mobilized at low axial deformations.
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