Soils are mostly weak in tensile strength and need to be strengthened by adding tensile elements. In the past decades several methods have been proposed to improve the soil mechanical properties. About the important of soil can be express that the soil reinforcements also technically and economically most cases is advantage over other methods. Structural point of view, due to the armed soil flexibility and high damping, which has good performance in front of earthquakes at their leaves instead of economically because of the ease of implementation, execution and low cost of the necessary materials (soil and Armed visitors), using this method can be adhered to the first preferences. Another important direction of the soil reinforced in which this method of granular soil and cohesive soil as a material involved with reinforced elements can be used. One of the proposed methods is the soil reinforcement which was introduced by Henri Vidal in 1960. Reinforced elements as strips, grids, wires, fabrics, felt, etc. from Steel, aluminum, plastics, polymeric materials have been used for this purpose. Geogrids which entailed a group of geosynthetic products are used widely as soil reinforcements to enhnce the soil bearing capacity and reduce its settlement due to footing loads. Extensive research has been done on the reinforced soil with geogrids which mostly involved with the same length of reinforcements in all layers (as a uniform block with depth). However, regarding the predicted sliding zones in the supporting soil of footings, it appears that the longitudinal arrangement of reinforcement layers with depth could affect on the footing bearing capacity. The main purpose of this research study was to investigate the likely effects of variations in geogrids arrangements placed in a sandy bed on the footing bearing capacity. In order to achieve this purpose, using gegrids reinforcement layers the bearing capacity of footing models was evaluated for uniform and non-uniform reinforcement arrangements. Three different reinforcement blocks were selected for considering nonuniform arrangements; the first group included the arrangements in which the length of geogrid layers increased with depth (trapezoidal state), the second included the arrangements in which the length of geogrid layers decreased with depth (inverse trapezoidal state), and the last group included variable increase and decrease of geogrids length with depth (variable state). The influences of footing shape including circular, square and strip forms on the bearing capacity were also considered. In addition, the effects of the soil bed density on the footing performance were investigated.
