The vertical bearing capacity of grillage foundations in sand

Grillage foundations have been suggested as an alternative to flat plate foundations for seabed infrastructure such as pipeline end manifolds and pipeline end terminations. These foundations have the advantage that they can be installed in an offshore environment more quickly because of their hydrodynamic properties. Seabed infrastructure is typically subjected to a combination of vertical, self-weight loading and horizontal loading from pipelines, snag loads or hydrodynamics and so the combined vertical-horizontal capacities of the foundations are critical. However, little is known about the capacity of grillage foundations either to purely vertical loading or to combinations of load. This paper reports a series of physical model tests designed to address this knowledge gap. The experimental methods are presented first followed by typical results showing drained foundation capacity for pure vertical loading.