Limit load space of rigid strip footing on sand slope subjected to combined eccentric and inclined loading

The stability of a footing-on-slope system under coupled eccentric and inclined loading is a significant concern in urban areas, especially in geotechnical engineering. To evaluate the ultimate bearing capacity of an eccentrically inclined loaded footing placed on a sand slope, the rigid plastic finite element method (RPFEM) was employed, and several analyses were conducted. Due to the asymmetry of the footing-slope system, an interface element was introduced to accurately calculate the contact stress between the footing and the soil for two eccentric directions, namely, positive and negative eccentricities. The study focused on assessing the influence of the soil strengths, such as the internal friction angle and soil unit weight, the footing width, and the slope geometry, including slope angle, slope height, and edge distance, on the three-dimensional V-H-M limit load space (vertical load – horizontal load – moment) to determine the uniqueness of this limit load space. In particular, the influence of the combination of two eccentric directions and two horizontal load directions, namely, positive horizontal load and negative horizontal load, on the V-H-M limit load space was investigated. The obtained results of the RPFEM indicated that the positive eccentricity and positive horizontal load had a positive effect on improving the bearing capacity of the strip footing on the slope crest. However, the results also showed a negligible effect on the bearing capacity as the edge distance increased up to a certain threshold value. The applicability of the V-H-M limit load space was thoroughly examined for several loading paths, and it was discovered to be unique for each soil strength and slope geometry parameter.