Abstract: The current design guide FHWA-NHI-10-024 (Design and Construction of Mechanically Stabilized Earth Walls and Reinforced Soil Slopes) is based on the LRFD (Load and Resistance Factor) concept, and the previous version FHWA-NHI-00-043 (Mechanically Stabilized Earth Walls and Reinforced Soil Slopes Design and Construction Guidelines) is based on the limit equilibrium theory. In this paper, a detailed comparative analysis on the differences between the two design methods is presented by computations in terms of slip resistance, base resultant force eccentricity, lateral earth pressure K_r and pull-out stability. By computation examples, the development trend of FHWA design methods for reinforced earth retaining wall is obtained. Result shows that the limit-equilibrium-based method is conventional and differs greatly from the actual working condition of retaining wall; while the LRFD-based method is economical and safe, and is in consistency with the actual working condition. The design concept of LRFD is related with limit state method, which indicates that the design method for reinforced retaining wall is developing towards limit state method.

Key words: FHWA, reinforced earth retaining wall, design guide, comparative analysis