Investigating the Bearing Capacity of Shell Foundations at Various Distances From the Edge of a Slope Reinforced With Geogrid

This study experimentally investigates the bearing capacity behavior of triangular shell strip footings located near geogrid‐reinforced slopes, with particular emphasis on the combined effects of footing geometry, reinforcement configuration, and footing setback from the slope crest. A comprehensive small‐scale laboratory program comprising 222 tests was conducted on sand embankments, considering four footing apex angles ( i  = 60°, 90°, 120°, and 180°), one‐ and two‐layer geogrid reinforcement systems, ratio of the depth of first geogrid layer ( u / B ), interlayer spacing ratios ( h / B ), and edge distances ( X / B  = 2, 3). To provide a comprehensive evaluation, the newly obtained experimental results for edge distances of X / B  = 2 and 3 are systematically compared with the baseline data for flat and sloped backfills with X / B  = 1 previously reported by [Hamidi A, Niknezhad MS, Asemi F, Sadrjamali M (2023) Bearing capacity of triangular shell strip footings on geogrid‐reinforced slopes. Arab J Sci Eng 48: 12709–12724. https://doi.org/10.1007/s13369-022-07475-0 ]. The results show that reducing the apex angle markedly improves the bearing capacity and settlement efficiency of the footing system, with the 60° shell footing consistently outperforming the flat footing. Increasing the edge distance from the slope crest significantly enhances the ultimate bearing capacity; for the 60° shell footing, increasing X / B from 1 to 2 and 3 led to bearing capacity increases of ~60% and 110%, respectively. The optimum embedment depth of the first geogrid layer was found to depend strongly on footing geometry, increasing as the apex angle decreased, whereas the optimum values in sloped backfill remained nearly unchanged between X / B  = 2 and X / B  = 3. For the two‐layer system, the additional contribution of the second geogrid layer was consistently positive, with the incremental benefit ratio ranging from 1.40 to 2.14 under the investigated optimum configurations. The results further show that shell footings provide superior settlement‐to‐capacity performance relative to flat footings, particularly in sloped backfills. A capacity‐normalized carbon‐efficiency assessment also indicates that the optimum 60° shell footing can reduce concrete carbon intensity per unit bearing capacity by ~59.8% to 76.6% relative to the flat footing. Overall, the study demonstrates that the simultaneous selection of footing geometry, edge distance, and reinforcement configuration is essential for achieving efficient and sustainable foundation design near slopes.