Only a limited number of geotextile-reinforced soil (GRS) structures have been constructed as important permanent structures supporting heavy load, such as bridge abutments and piers, due to their relatively low vertical stiffness. To alleviate this problem, the preloaded and prestressed (PLPS) reinforced soil method has been proposed. To evaluate the seismic stability of PLPS GRS structures, a series of shaking table tests of small models were performed. It is shown that the seismic stability of PLPS GRS structures becomes very high by proper preloading and prestressing. Resonance of the structure to seismic load can be avoided by maintaining a high natural frequency of the structure with a high prestress. A measures to maintain a sufficiently high prestress during strong shaking is presented.
Geotextile-reinforced soil (GRS) structures have a reputation in a high cost-effectiveness. However, the vertical stiffness of GRS structures could be insufficient to be used as critical permanent structures, such as bridge abutments and piers that allow only small deformation. To alleviate this problem, the preloaded and prestressed (PLPS) method has been proposed (Figure 1: Tatsuoka et al., 1996, Uchimura et al., 1996, 1998). In this construction method, after a full-height of structure is constructed, a large vertical preload is applied to the backfill by means of tie rods fixed to upper and lower reaction blocks. The vertical load is then decreased to a prescribed prestress level before opened to service. The first prototype PLPS GRS structure was constructed as a 2.7 m-high bridge pier for a one-track railway in Kyusyu, Japan (Figure 2). The pier supports two 16.5 m simple beam girders with a dead weight of 390 kN for each. The backfill is a densely compacted well-graded crushed gravel, reinforced with geogrid layers with an average vertical spacing of 15 cm.
