Strength and Bearing Capacity of Ring Footings Resting on Fibre-Reinforced Sand

Stress–strain response of fibre-reinforced and unreinforced sands has been studied by using large direct shear and drained triaxial shear tests. Influence of fibre content (0.50, 0.75, 1.00, and 1.25%), normal stress (for direct shear) and confining pressure (for triaxial shear test), relative density of the unreinforced and fibre-reinforced sand (medium i.e. 50%, and dense i.e. 70%) has been studied. Moreover shear strength parameters obtained from direct shear and triaxial shear tests have been used to calculate the Ultimate bearing capacity (UBC) of ring footings by proposing an empirical expression. UBC calculated theoretically, by using the shear strength parameters obtained from direct shear and triaxial shear test, has been compared with the experimental UBC. Fibres inclusion in the sand not only increases the shear strength of sand-fibre matrix but significantly improves the stress–strain response. Shear strength parameters obtained from direct shear tests have been found to be lesser than that of the triaxial shear test. UBC calculated, using shear strength parameters, from triaxial shear test gave more conservative values than that of the direct shear test.