Upper-Bound Bearing Capacity of Strip Footings Rested on Unsaturated Sands and Subjected to Eccentric and Inclined Loading

This article deals with the load-bearing capacity of strip foundations resting on unsaturated sands and subjected to eccentric and inclined loading. The numerical simulations are performed by modifying the conventional finite-element upper-bound limit analysis available for saturated soils. This modification is carried out with the help of the suction stress-based effective stress tensor and by redefining the Mohr–Coulomb yield circle and yield envelope in the three-dimensional space system. The spatial variation of matric suction in the vadose zone is developed based on the van Genuchten soil water characteristics curve and Gardner’s one-parameter hydraulic conductivity function. By considering a wide range of soil strength and unsaturated soil properties, a rigorous parametric study is carried out to investigate the combined effect of loading position and orientation on the ultimate bearing capacity of the strip foundation rested on an unsaturated medium. The fluctuation of the groundwater table and the variation in the climatic conditions are duly considered. The solutions are presented in terms of ultimate bearing capacity charts. The nodal velocity contours are drawn for several cases. The obtained numerical solutions are in good agreement with the results presented in the available literature.