Performance of loosely skirted square footing resting on reinforced sand under vertical concentric and eccentric loading

Abstract

ABSTRACT The present study investigates the performance of loosely skirted square footing resting on multi-layered geo-grid reinforced medium dense sand under vertical concentric and eccentric loading through a series of laboratory model tests. The load eccentricity (e) is varied as 0, 0.1B, 0.15B, 0.2B (where B is the width of the footing). Parametric variations like depth of skirt (d = 1B, 1.5B, 2B), number of geo-grid layers (N; varies with variation of depth of skirt), spacing between horizontal reinforcements (Y = 0.25B,0.5B,0.75B,1B) have been investigated with a constant surface dimension D/B = 1(D is the top surface dimension of the skirt). The test results show that load intensity increases significantly with the increment of skirt depth and approaches the optimum value at d/B = 2 for a spacing of 0.25B for both the loading conditions. However this increment is less prominent for footing with only skirt and without reinforcements. Increment in number of horizontal reinforcements too showed an increase in bearing capacity and reduction in settlement. Effect of eccentricity on load intensity for both concentric and eccentric loading has been compared in the present experimental work. The improvement in bearing capacity and reduction in settlement of the footing has also been assessed in terms of bearing capacity ratio (BCR) and settlement reduction factors (SRF). Even while comparing the economic aspects, geogrid skirts prove to be a viable alternative to the conventional skirts