Development of a pioneering foundation system for a 225 000 m LNG storage tank in Canada by using driven closed-ended steel piles non-connected to the concrete slab (rigid inclusions)

This paper presents the optimisation of the foundation system of a LNG storage tank of 225 000 m³ volume, built in Kitimat, Canada. Site geology consists of a 160 m thick alluvial deposit, composed by alternating layers of clayey silts and gravelly sands. Surficial deposits are prone to liquefaction due to their low density and the high seismic activity in the area. To mitigate this risk, the design was optimised to a system of rigid inclusions, instead of the initial system proposed in the FEED, consisting of a piled foundation with a system of stone columns. This system was innovative in the LNG industry as it was the first time it was used for a LNG tank of such dimensions.

The robustness of the design has been confirmed by the performance of: CPTs after pile installation, confirming the increase of soil density; static and dynamic pile tests, validating the pile bearing capacity; and, monitoring of tank settlement, verifying that settlements are within the criteria defined in the project specifications.