Parametric Studies on the Behaviour of Reinforced Soil Retaining

(c) York Wall Facing (Jones, 1994) (d) L-shaped Concrete Facing (Broms, 1988)
(e) Reinforced Concrete Panel (Japanese System) (f) Full Height Reinforced Concrete Facing
Figure 2.11: Currently Used Typical Facings in Reinforced Soil Structures (Jones, 1994)
Tatsuoka et al. (1992) studied the effect of facing rigidity in a set of GRS-RWs
model tests having facing Types A, D. The test result reveals that the location of
failure surface moved from an intermediate elevation to the bottom of the facing
depending on the facing rigidity. The tensile force just behind the facing is greatly
influenced by the facing rigidity. Location of (Fig. 2.10) approaches back of
the facing with increasing facing rigidity. Thus, the contribution of the facing rigidity
on the stability of the reinforced soil structure was clearly demonstrated and several
other researchers (e.g., Juran-Schlosser, 1979, Bolton-Pang, 1982, and Koga et al.,
1992) report similar conclusions.
2.6 Typical Current Design Methods
For the analysis and design of reinforced soil structures numerous approaches have
been developed. All methods are either empirical in nature or based on limit
equilibrium analysis. These methods do not consider either the stress-deformation
characteristics of the structure or the interactions between the wall components e.g.
the soil, the reinforcement, the facing and the foundation. Their main purpose is to
compute the factor of safety against several modes of failure. In general, the design
methods use the allowable strengths (corresponding to each component) which are
significantly lower than the ultimate strengths and further partial safety factors are
applied to account for the uncertainties in the behaviour of the reinforcement and
soil/reinforcement interaction mechanism. Consequently, these methods are lagging
in adequately describing the real behaviour of the reinforced soil structures. Hence,
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