When designing structures that will impose a significant load over a large area, such as buildings, tanks, walls, slopes or embankments, geotechnical engineers must address the following situations, especially when dealing with weak foundation soils: bearing capacity failures, intolerable total and differential settlements, large lateral pressures and movement, and slope instability. The construction of reinforced soil foundations to support a shallow spread footing has considerable potential as a cost-effective alternative to conventional methods of foundation support. With this technique, more than one layer of geogrid reinforcement is placed within layers of engineering fill material under the footing to create a composite material with improved performance characteristics. Here an attempt is made to present the details of an investigation of the performance of geogrid reinforcement in soil. For this purpose, model isolated footing load tests were conducted on soil with and without multi-layers of geogrid at different depths below the footing. The load settlement characteristic for
each soil-geogrid configuration was observed. The influence of various selected parameters on the load settlement behavior were studied and critically appraised for their practical significance. The paper discusses the mechanisms of this system using a large-scale model footing for a case studies in which geogrid-reinforced soil footing is used for a schools project in Saudi Arabia. That site has a very soft silty clay/clayey silt soil, and the large-scale plate loading test was tested according to the procedure of ASTM D1194. Also, the paper presents the successful application in the use of geogrid-reinforcement. The field observations proved that the geogrid-reinforced system creates an enhancement to the very soft/soft soils and minimizes the differential settlement. The geogrid-reinforced system is more economic and attractive and demonstrates superior performance compared with most other ground improvement techniques and is optimal for rapid construction and/or strict total and differential settlements of the structure and/or a thick and newly
placed fill.