Undrained stability of surface strip footings above voids

This paper investigates the undrained vertical bearing capacity of surface strip footings on clay with single and dual continuous voids. Numerical solutions for a wide range of geometric and material combinations are obtained by small strain finite element analysis. Based on the results, design charts are provided for the calculation of the undrained bearing capacity factors as a function of the dimensionless parameters related to the vertical and horizontal void distances from the footing, void width and height, and spacing between the two voids as well as soil rigidity and non-homogeneity. In the footing-above-void system, the ultimate bearing capacity of the footing is governed by the three failure mode: roof, wall, and combined failure mechanisms.