Experimental Investigation of Bearing Capacity of Strip Footing Rest on Layered Soils Next to the Geogird Reinforced Retaining Walls

In general, stable vertical or near-vertical soil embankments, natural and unnatural slopes near the roads can resist existing forces and when the stip loading act on near them, those can be unstable because of tension problem of soils, so increasing of tension resistance of soil is a very important problem in geotechniacal engineering. The use of reinforced soil to design of foundations and soil structures such as retaining walls is an innovation that is considered as the most versatile and most economical problems for soil improvement. Despite numerous studies about the techniques of reinforced soil on lateral displacement of the retaining wall and bearing capacity of strip foundation located on the retaining wall under the soil homogeneity conditions, few studies have been carried out on these walls in the layered soil conditions. In this study small scale laboratory tests conducted to investigate the bearing capacity of strip footing rest on layered soil next to geogrid reinforced retaining walls. The results showed that increasing the number of reinforcement layers ,at appropriate intervals on the multi-layer embankment, decreases the lateral displacement of the wall and increases the bearing capacity of strip foundation and maximum amount of bearing capacity of footing can be achieved at u/B=0.25. Also the results showed that increasing the length of geogrid layer increases the bearing capacity of footing and the optimum length ratio is equal to 4 (L/B=4). Also when the first layer thickness of soil is greater than footing width the bearing capacity of footing depends on only first layer properties.