A novel technique to mitigate the effect of gapping on the uplift capacity of offshore shallow foundations

Abstract

A flexible mat was provided around the periphery of skirted shallow foundations, a so-called 'gap arrestor', to assess the potential to mitigate the effect of gapping on uplift capacity. Results are presented from a series of drum centrifuge tests on skirted foundations with an intact skirt-soil interface, a gapped skirt-soil interface and a gapped interface with gap arrestor, subjected to undrained and sustained uplift. The results are promising, showing that the provision of an effective gap arrestor preserves suction to larger foundation displacements and reduces the rate of displacement under sustained uplift compared with the case of a gapped interface without arrestor.

Experimental investigation of reverse end bearing of offshore shallow foundations

“…Mitigation measures might include provision of internal skirts to compartmentalise the soil plug, so that loss of suction would be limited to a single compartment or group of compartments rather than across the entire foundation footprint. A flexible mat might be provided around the periphery of the foundation to act as a sacrificial pseudo compartment, although the technology for so-called 'gap arrestors' has yet to be established in the field (Mana et al 2013b). It should also be borne in mind that very soft, normally consolidated clays may not be prone to gapping, so that reverse end bearing response corresponding to an intact skirt-soil interface can be relied on.…”

Applicability of the strain accumulation procedure for the geotechnical foundation design of zero-radius bend triggers

“…The ultimate undrained vertical resistance of the foundation is taken as qV,ult = 24 kPa and the targeted vertical (compressive) load applied to the foundation in the horizontal monotonic and cyclic tests was 0.2qV,ult. (Britto & Kusakabe, 1982, Mana et al, 2013b.…”