Seismic design of reinforced-earth and soil-nailed structures

Soil-nailed and reinforced-earth structures are systems that are coherent and flexible. Therefore, they offer inherent advantages in withstanding large deformations and, as illustrated by post-earthquake observations on soil-nailed retaining structures and reinforced earth walls, they prsent high resistance to earthquake loading. Owing to these advantages soil-nailed and reinforced-earth structures offer a valuable and cost-effective technical solution for geotechnical construction in seismic zones. However, to date, only limited studies have been conducted to evaluate the dynamic response of these structures. This paper presents the development and experimental evaluation of kinematical pseudo-static working stress analysis approach for the seismic design of soil-nailed and reinforced-earth walls with inextensible metallic reinforcement. The proposed method is derived as an extension of the kinematical working-stress approach developed for the design of reinforced-earth and soil-nailed structures subjected to self-weight static loading. It provides an estimate of the seismic loading effect on the location and magnitude of maximum tension and shear forces developed in the reinforcements under working stress conditions. The method is evaluated through comparisons with experimental results of shaking-table tests on semi-scale reinforced-earth model walls and centrifugal soil-nailed model tests. The predictions of the method are also compared with numerical simulations of semi-scale shaking-table model test results. Finally, comparisons between the proposed method and currently available pseudo-static design methods are presented with preliminary conclusions with regard to design practice.