A Study on Bearing Capacity of Circular Footing Resting on Geogrid Reinforced Granular Soil

This study has been conducted to investigate the effect of reinforcing on the bearing capacity of circular footing resting on granular soil. For this purpose, a total number of seven large-scale plate load tests were carried out on a circular plate with a diameter of 300 mm. In order to prepare specimens, a portable curtain rain system is used which is calibrated by 60 raining tests. In the current designed and developed experimental system, a new method is used to measure the normal pressure at footing base. In all loading experiments on soil reinforced with geogrid, only one geogrid layer is used and the effect of depth of this layer from footing base is investigated. The results showed that with provision of geogrid, the bearing capacity of circular footing increases up to 1.56 times of unreinforced mode. In addition, it is shown that by increasing the ratio of u/DF, the slope of load-settlement curve (stiffness) decreases. For values of u/DF>0.67, the effect of this parameter (dimensionless depth of geogrid) on bearing capacity of the footing is constant, which indicates that the reinforcing mechanism has been changed and the failure occurs at the upper soil mass (above the geogrid). Also, the results showed that with increasing of the distance from center of the footing, the value of normal pressure applied at footing base reduces.