UBC of Eccentrically Loaded Strip Foundation Resting on Geogrid Reinforced Sand

Abstract

Numerical model test results for the ultimate bearing capacity (UBC) of a shallow strip footing resting on geogrid reinforced sand subjected to eccentric vertical loading are presented in the study. The numerical modelling is carried out using finite element tool Plaxis 3D in which the footing of size 5 m × 1 m × 0.1 m (L × B × t) is modelled as plate element which rests on soil volume of 5.05 m × 11 m × 8 m (L × B × H). Deep footing mechanism (i.e. width of reinforcement b is equal to the width of the footing B) is adapted in the present study. Several influencing parameters like relative density of sand (Dr, %), embedment ratio (Df/B), eccentricity ratio (e/B) and number of reinforced layers (N) have been considered to observe the UBC of the footing. 216 numbers of numerical model conditions have been developed where Dr (%) varies from 25 to 75% @25%, Df/B varies from 0 to 1 @0.5, e/B varies from 0 to 0.15 @0.05 and N varies from 0 to 5 @1. The Plaxis model is created and analyzed, following HS Small model. The study reveals that irrespective of Df/B and e/B, among all the simulated conditions, the influence of reinforcement is significant for Dr = 25%. It is observed that the failure envelope is shifting from symmetry to one side as the loading is changing from centric vertical to eccentric vertical. The optimum number of reinforced layers (N) for all the cases was found to be in the range of 2–3, after which the effect of reinforcement seems to have marginal effect on the UBC of the footing.