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Due to the increase of population and limitation of land resource, it is a common practice nowadays to see developments over unfavorable sloping terrains in the modern urbanization. The developments mostly include residential and commercial buildings which are commonly supported on footing foundations. Bearing capacity of footings on level ground can be analyzed with the well-established classical bearing capacity equation. Modification factors to the existing classical equation are available in literatures to estimate bearing capacity of footings on the crest of sloping ground. However, bearing capacity on slopes is more complex which depends on several factors including slope angle, setback distance from crest of slope, soil parameters, and footing size. Previous studies also mainly consider shear failure based approach. However, deformation along the slope plays a major role in governing the failure of such foundations, thus requiring a coupled stress-deformation based failure analysis. In this research, effect of sloping ground on bearing capacity of square footing was investigated using 3D numerical model by systematically varying the factors affecting the bearing capacity. The classical bearing capacity equation of footing is expressed as the summation of three terms which are namely cohesion, friction and depth terms. The effect of slope on the cohesion and friction term was studied by considering footings on surface of cohesive soil, in undrained condition, and cohesionless soil, in drained condition for various combinations of slope angle, setback distance, cohesion, angle of internal friction and footing size. For the cases considered in this study it was obtained that beyond a critical setback distance to footing width ratio of 0.75 and 2, the effect of slope on the failure mechanism and bearing capacity of a square footing diminishes for cohesive and cohesionless soils, respectively. The simulation results were used to establish relations of improved modification factors with respect to slope angle, setback distance from slope crest, footing size, and soil shear strength parameters. The proposed models were compared with the existing modification factors in literature and simulation data. |
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