Bearing Capacity of Rectangular Footing Resting Over Geogrid Reinforced Sand Under Eccentric Loading

Abstract

A number of works have been carried out for the evaluation of a ultimate bearing capacity of shallow foundation, supported by geogridreinforced sand and subjected to centric load. Few experimental studies have been made on the calculation of bearing capacity of shallow foundation on geogrid-reinforced sand under eccentric loading. The purpose of this research work is to conduct model tests in the laboratory by utilizing rectangular surface foundation resting over the reinforced sand. The model tests have been conducted using rectangular footing with B/L=0.5 & 0.33. The average relative density kept up throughout all the tests is 69%. The sand is reinforced by multiple layers (2, 3 & 4) of geogrid. The eccentricity varies from 0 to 0.15B with an increment of 0.05B. Distance of first layer of geogrid layer from bottom of footing and the distance between two consecutive geogrid layers have been kept constant. The load settlement curve for each tests have been plotted to calculate ultimate bearing capacity.Parametric studies have been made to find the impact of eccentricity on bearing capacity of the foundation. The ultimate bearing capacity of eccentrically loaded square footings can be computed by knowing the ultimate bearing capacity of square footing under central load and a reduction factor (RkR)for reinforced condition. The reduction factor is developed based on the results of laboratory model tests on geogrid reinforced soil. The ultimate bearing capacity of eccentrically loaded rectangular footing resting over geogrid reinforced sand can be calculated by knowing the ultimate bearing capacity of rectangular footing resting over reinforced sand bed and subjected to central vertical load by using reduction factor (RkR). An equation for reduction factor for rectangular footing resting over geogrid reinforced sand is developed based on laboratory model test results.