15,000m2 of Vibro Replacement stone column densification to a treatment depth of 9m
Port Metro Vancouver is constructing a Container Examination Facility on Tsawwassen First Nations industrial land in Delta, BC. The CEF comprises a 60m x 150m warehouse, office buildings and paved yard areas.
In general, the soil profile at this site comprises 0.8 to 2.1m of native silt, underlain by silty sand, transitioning into loose to compact clean sand interlayered with silty sand / sandy silt to the depth investigated. Depth to ground water was reported to range from 0.3m to 1.5m.
Ground Improvement Solution
The Engineer’s analysis indicated the foundation soils were susceptible to liquefaction during the 1:2475 year design seismic event. To mitigate the risk of crust rupture and punching failure of spread footings, ground improvement was required to 9m depth below footing elevations.
Wet top-feed Vibro Replacement stone columns was selected as the most appropriate ground improvement technique. Stone columns were installed on a regular grid pattern covering the extent of the foundation footprint and extending 9m beyond the foundation perimeter.
Post-densification CPT testing demonstrated the wet top-feed Vibro Replacement methods successfully achieved the specified performance based requirements.