The metastability of some gull-fill materials from Allington, Kent, UK

Samples of infill material from gulls in the Hythe Beds at Allington, Kent, England, were tested to determine their geotechnical index properties and their susceptibility to collapse when wetted under load in an oedometer. The soils accumulated during Late Devensian, late Pleistocene, times within a periglacial environment. They probably represent, at least in part, an overlying layer of brickearth type material that gradually subsided into the gulls as the ice that occupied them melted with the onset of warmer conditions. The soils resemble, both in colour and their index properties, brickearth found elsewhere in Kent and in south Essex. All the gull-fill sample material had silt contents in excess of 75%, low dry densities (1.4 - 1.7 Mg m-3), medium to high porosities (35 - 47.5%) and carbonate contents below 0.5%. The results from the oedometer collapse tests showed that one of the samples was non-collapsible and that the others were conditionally collapsible. When these results were compared with several empirical collapse criteria, all derived from basic geotechnical soil properties, only some of the criteria showed reasonable agreement with the oedometer results.