Bearing Capacity of Clayey Soil Reinforced with Geogrid

Foundations constructed on soil deposits, cohesive in nature or having plasticity, result in low load-bearing capacity, and settlement exceeding permissible value. This may cause structural damage and reduction in the durability of structure. Conventionally the weak cohesive soil was either excavated and replaced with layer of stronger granular material or the size of footing was increased, or both the methods were adopted. These methods are uneconomical and time-consuming. Further, stability of cohesive soil is difficult because of low permeability which takes substantial time to consolidate. Therefore, the use of geosynthetic material has emerged. This study shows the results of laboratory investigation on square footing resting on clayey soil of medium plasticity reinforced with Geogrid. A square footing of dimension 75 mm x 75 mm made of mild steel is used. The important parameters that were examined in this study include the vertical distance between the base of footing and first geogrid layer, the number of geogrid layers, the vertical distance between each geogrid layer and its effect on the ultimate bearing capacity. All the experiments were conducted in a steel tank with transparent acrylic sheet in front. The results of tests performed showed that with the incorporation of geogrid in soil increases the bearing capacity as compared to unreinforced soil. The optimal distance of the top geogrid layer from bottom of footing was found to be 0.35B. There was increase in bearing capacity with increase in geogrid layers, however this effect decreases with increase in layers beyond influence depth. Bearing capacity of the soil reduces with increase in the vertical distance between the geogrids.