Stability charts for sustainable infrastructure: Collapse loads of footings on sandy soil with voids

The presence of underground voids in regions suitable for sustainable development can adversely affect the stability of the overlying infrastructures. In this paper, the collapse loads of strip rigid footings resting on sand with single and double continuous voids are determined for a frictional Mohr-Coulomb material following the non-associated flow rule. For use by practitioners, design charts are proposed to evaluate the well-known bearing capacity factor N_γ as a function of the dimensionless parameters related to the vertical and horizontal void distances from the footing, void shape, and spacing between the two voids, as well as the soil friction angle. The computational result compares quite favorably with the available theoretical and numerical solutions. The failure mechanism is broadly discussed based on the pattern of soil displacement around the footing and void.