Geogrid Reinforced Granular Pad Foundation Resting on Loose and Soft Soils, Hamilton Harbour, Ontario

Abstract

The waterfront quays in Hamilton Harbour have been constructed by placing upfill within a perimeter steel sheet pile bulkhead. The fill materials are believed to consist of dredged material loosely placed on the original harbour bed, within the enclosure. The quayside had been used for general dock activities, including stockpiling discharged ships’ cargoes. Recently, two 31 m diameter liquid storage tanks have been constructed on the site; the stored liquid applies a load of 120 kPa to the ground surface. Based on borehole data developed in an initial geotechnical investigation of the site, it was recommended that the tank loadings be supported on either stone columns or end bearing pile foundations. The cost of these foundation systems was prohibitive to the development. Additional fieldwork consisting of three soundings with a Marchetti flat plate dilatometer was carried out to better define the geotechnical properties of the soil profile. Using these data, a foundation design was prepared which consisted of construction of a geogrid reinforced granular pad. Post construction monitoring of settlement of the tank foundation shows that settlement of the foundation has been within tolerable limits.