DESIGN AND CONSTRUCTION OF A THREE-STOREY CONCRETE BUILDING ON LIQUEFIABLE SOILS IN VICTORIA, BC

ABSTRACT: The foreshore in Victoria has undergone a number of changes over the years with large areas of fill having been placed to increase the land surface within much of the foreshore area. One such reclaimed land site was selected for the construction of a new three-storey concrete building. The field investigation consisted of both Becker Penetration tests (BPT) and Standard Penetration Tests (SPT) followed by bedrock probing with an air track percussion rotary drill. The soil conditions generally consist of a variable thickness of gravelly sand to sand and gravel fill material overlying a thick deposit of firm to soft marine clay. The design level earthquake for this structure is the 1:2,475 year event which results in a peak horizontal firm ground acceleration (PGA) of 0.6 g for this site. Estimated liquefaction induced lateral displacements within the fill were up to 6 m and vertical settlement estimates varied from about 0.1 m to 0.3 m. The final design of the building foundations consisted of rock-socketed caissons designed to resist the seismic deformations. Additional challenges included planning and executing a geotechnical investigation within a congested active work site and meeting the environmental requirements for working adjacent to the ocean within contaminated fill.