Bearing Capacity of Embedded Foundations

Exact closed form solutions based on plasticity theory are available for a strip footing resting on homogenous Tresca soil subjected to pure vertical load. Variations from this situation are normally dealt with using modification factors, such as factors for embedment, load inclination, foundation shape and soil strength profile. While these have been derived numerically for simple footing configurations, few solutions are available for non-standard footing shapes and for problems involving progressive embedment. This paper investigates the plane strain bearing capacity factor (Nc) of block and cylindrical embedded footings at various depths in a clay soil and examines the effect of progressive embedment, an issue particularly relevant in offshore geotechnics. A novel automatic numerical procedure, Discontinuity Layout Optimisation, is adopted to obtain optimal slip line mechanism solutions for footings at various embedment ratios. The cylindrical footing simulations are compared with a series of 1g experiments on pipelines, both in terms of load capacity and kinematics, which were determined in the experiments using digital imaging through a transparent side wall in conjunction with PIV processing.