Laboratory model study on geosynthetic reinforced soil retaining walls

Reinforced soil technologies have been extensively used during the past few decades in the construction of embankments and retaining walls. A large variety of reinforcing materials emerged and have been developed for construction purposes, including: metal strips, bar mats, geotextile sheets, geogrids, etc. Fullscale experiments and centrifugal and reduced-scale laboratory model studies have been performed to provide a rational basis for design methods of reinforcing systems using quasi-inextensible steel strips and bar mats. However, laboratory model studies on the behavior of reinforced soil walls with more extensible reinforcements, such as geotextiles, and geogrids, have been rather limited. These studies have encountered fundamental difficulties pertaining to similitude requirements and specifically appropriate modeling of the reinforcing materials, as well as to the proper instrumentation of extensible reinforcing elements to measure the mobilized tension forces. This paper describes the results of a laboratory model study on the performance, behavior and failure mechanisms of reinforced soil-retaining walls using different reinforcing materials, namely: woven polyester geotextile strips, plastic grids, and nonwoven geotextile strips. The model walls were instrumented to obtain measurement of stresses in the reinforcements, displacements at different points along the reinforcements, displacements of the facing, and to identify, using colored sand, the failure surface in the soil. Experimental results indicate that the confinement of the reinforcement has a major effect on the structure performance. The paper also outlines practical conclusions that can be drawn for design purposes.