Influence of soil fabric anisotropy on the bearing capacity of geosynthetic-reinforced foundations under eccentric and inclined loadings

Abstract

This study aims to explore the significant impact of soil fabric anisotropy on the ultimate bearing capacity of eccentrically and obliquely loaded shallow foundations overlying a geosynthetic-reinforced granular deposit. For this purpose, the well-established lower bound theorems of limit analysis (LA) in conjunction with the finite elements (FE) formulations and second-order cone programming (SOCP) are exploited to perform the bearing capacity estimations. The consideration of the soil mass’s inherently anisotropic response in the granular layer involves the utilization of distinct internal friction angles in various directions. The lower bound FELA framework adopted in this study incorporates both the pull-out and tensile mechanisms of failure in the reinforcement layer. The marked contribution of soil inherent anisotropy to the impacts of ultimate tensile strength ($T_u$) and embedment depth ($u$) of the geosynthetic reinforcement on the failure mechanism, bearing capacity ratio (BCR), and failure envelope of the overlying obliquely/eccentrically strip footing is rigorously examined and discussed. It is generally concluded that for a given embedment depth, failure envelopes of the surface footing in both $V$-$H$ and $V$-$M$ planes shrink appreciably with the increase in the soil anisotropy ratio as well as the decrease in the geosynthetic ultimate tensile strength. Moreover, the influence of soil inherent anisotropy on the overall bearing capacity of shallow foundations is more evident in the case of using strong reinforcement compared to the weak geosynthetic. The findings of this investigation demonstrate that overlooking the soil inherently anisotropic behaviour in the numerical analysis of shallow foundations would give rise to undesirable non-conservative and precarious designs.