Seismic Deformation of Bar Mat Mechanically Stabilized Earth Walls. I: Centrifuge Tests

Altogether six mechanically stabilized earth walls were subjected to many base excitations on the National Geotechnical Centrifuge at the Univ. of California, Davis. The walls supported dry cohesionless soils deposited at the start of the test at a relative density of 65%. In general, walls behaved as expected, i.e., walls with longer reinforcement deformed less, than the walls with shorter reinforcement. There was no catastrophic failure observed in any of the six walls. The wall face displacement was not uniform across the wall face, and typically the middle of the wall displayed the largest displacement. The acceleration response near the top of the wall showed "clipping," and during this time the lateral wall movement occurred away from the backfill. Such behavior was not observed either near the bottom of the wall or in locations away from wall, i.e., free field. Measurements show a lack of rotation near the top of the wall, while the bottom of the wall moved laterally and rotated. The acceleration field in the backfill, even within the wall height of 7.3 m studied here, is not uniform and a substantial deamplification occurred when base acceleration level increased above 0.4g. The observations such as nonuniform wall face deformation, wall rotation at the bottom of the wall, and amplification (or deamplification) in the backfill are important factors that should be accounted for in analytical models for wall deformation.