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Influence of upper tier on the reinforcement forces in the lower tier in a two-tiered reinforced soil retaining wall

Geosynthetic reinforced soil retaining walls are widely used in recent years due to their suc-cessful functional behavior, economy, and ease of construction, compared to conventional reinforced con-crete retaining walls. Multi-tiered reinforced soil retaining walls are often considered superior to those with single tier of same heights in terms of efficiency, aesthetics, reliability and economy. Current design approaches such as Federal Highway Administration (FHWA) and National Concrete Masonry Associa-tion (NCMA) suggested their guidelines that are empirical and derived on the basis of the offset distance between upper and lower tiers. The interaction between the two tiers is not technically explained. In this paper, the finite element analysis of two tiered MSE wall with various levels of offset distance is carried out using PLAXIS 2D software. The influence of upper tier on the maximum tensile forces in the rein-forcement layers of lower tier is studied and compared against the same configuration of walls designed according to NCMA and FHWA design approaches. The critical offset distance (the offset distance be-yond which the influence of the upper tier on the reinforcement forces in the lower tier is negligible) of the two tiered retaining wall is studied. It is observed that the magnitudes of reinforcement forces obtained from finite element analysis are less compared to those of other two design approaches.