EFFECT OF WALL ASPECT RATIO ON SEISMIC RESPONSE OF NARROW MECHANICALLY STABILIZED EARTH WALLS

Increasing population and expanding urban development in limited spaces involves construc-tion of Narrow Mechanically Stabilized Earth (NMSE) walls having an aspect ratio (ratio of reinforcement length, L, to wall height, H) below 0.70. When constructed in seismically ac-tive zones, these walls are subject to seismic ground motions. The purpose of this paper is to present the results of small scale shaking table tests on NMSE walls with rigid facing. A se-ries of reduced scale (1/8 of the prototype model) shaking table tests are performed on a 1-dimensional shaking table. The modeled walls have aspect ratio (L/H) of 0.20, 0.30 and 0.40. The model is shacked using ramped sinusoidal base accelerations with incrementally increas-ing displacement amplitude (i.e. actuator stroke) and constant frequencies to generate an equivalent base acceleration ranging from 0.05 g to 0.70 g or until failure occurs. Ground mo-tion frequency of 2.5 Hz is used. The results show that at input accelerations ranging from 0.25g to 0.45g yielding occurs and the NMSE walls behaves as a rigid body. Subsequently, excessive deformations occur due to the pull out of the top reinforcement layers. An amplifi-cation factor of 2.50 times the input ground motion is measured at the surface of the NMSE models. Furthermore, the average design acceleration for the model walls ranges from 1.02 to 1.35 of the input base acceleration.