94. Seismic Stability of Preloaded and Prestressed Reinforced Soil Structures

This relates to the development of techniques to improve the seismic stability of geosyntheticreinforced bridge piers using novel systems of preloading and prestressing. These techniques hold great proise to reduce deformations of reinforced piers under traffic loading and during earthquakes. The work has been validated by both full-scale field structures and laboratory model tests using a shaking table. The preloading and prestressing (PLPS) procedure was originally developed to substantially decrease the residual settlement at the top of backfill subjected to long-term live loads such as traffic loads. Furthermore, a novel aseismic system of the preloaded-prestressed reinforced soil method was proposed and validated. Using this method, it is now possible to construct reliable and critical civil engineering structures such as geosynthetic-reinforced soil structures (i.e., bridge abutments and bridge piers). In this procedure, a sufficiently large vertical preload is applied to the reinforced backfill by introducing tension into metallic tie rods that penetrate the reinforced backfill with the ends fixed to the bottom and top reaction blocks. In addition, the stiffness and strength of the backfill, while the structure is in service, is always kept sufficiently high by maintaining sufficiently high prestress. By this pre-loading and prestressing construction procedure, the transient deformation of reinforced backfill subjected to traffic loads could become very small and essentially elastic and, thereby, the long-term residual deformation could become minimal.