Investigation of soil amplification on geosynthetic reinforced soil retaining walls

Abstract

Geosynthetic Reinforced Soil Retaining Wall concept is basically reinforcing a soil mass to form a wall from the soil which has a little tensional strength. These structures have been used all around the world for nearly four decades right now and their dynamic performance has been tested with models and on the field by observation. So far their dynamic response performance is promising. The amplification of accelerations is one of the issues which have been determined during both experimental and numerical studies. In this present study the aim is, to observe the amplifications relativity due to the materials used as natural fill, backfill, base soil and the design of the geosynthetic reinforcements. A commercial Finite Element Method program Plaxis v8.2 is used to conduct analyses on 9 different models with 4 different soil types. These soil types are defined as rock, stiff sand, sand and clay. A geogrid was used as reinforcement and the wall facing is selected as a concrete plate. Prescribed displacements method was used with a harmonic earthquake motion in order to conduct dynamic analyses. The analyses have resulted in that the accelerations are most amplified at places close to the top and to the face of the wall. Clay has shown a better performance as a backfill material compared to sand in amplification of accelerations, deformations, axial forces. Clay also has a de-amplification effect in the depths of the medium. The general conclusion is walls designed according to the current specifications behave successfully under earthquake loading conditions and amplification of accelerations are heavily affected by the soil properties.