Performance and Analyses of Mechanically Stabilized Earth Walls in Tecomán, Mexico, Earthquake (05-1723)
Joseph Wartman, Drexel University

This article discusses the performance and analysis of four mechanically stabilized earth (MSE) wall bridge approaches shaken by the 2003 Tecomán, Mexico earthquake. Strong shaking during the earthquake caused varying degrees of permanent displacement in several of the MSE walls. Detailed damage surveys of each wall were made immediately after the earthquake by a geotechnical engineering reconnaissance team and complete design and construction data were later obtained. The analyses indicate that pullout of the upper reinforcement layers was the mechanism reasonable for the seismically induced deformation of the MSE walls. The upper layers of reinforcement were particularly vulnerable to pullout because of the low levels of confining stress and the fewer number of reinforcing elements per unit width. While pullout was the principal deformation mechanism, two other factors related to the earthquake ground motion also played a role in the damage. These include the large peak ground acceleration value, which was more than twice the design value, and possible directional effects in the ground motion, which directed significant energy toward the north-east. The latter finding concurs with observation made during the reconnaissance, where a clear directional bias was observed in the MSE wall deformations. The applicability and validity of the pseudostatic and sliding block methods of seismic analyses are discussed in light of the observed performance of the MSE walls.