Foundations in Permafrost of Northern Canada: Review of Geotechnical Considerations in Current Practice and Design Examples

Abstract

In northern Canada where permafrost is prevalent, a persistent shortage of accessible, affordable, and high-quality housing has been ongoing for decades. The design of foundations in permafrost presents unique engineering challenges due to permafrost soil mechanics and the effects of climate change. There is no specific design code for pile or shallow foundations in northern Canada. Consequently, the design process heavily relies on the experience of Arctic engineers. To clearly document the current practice and provide guidance to engineers or professionals, a comprehensive review of the practice in foundation design in the Arctic would be necessary. The main objective of this paper is to provide an overview of the common foundations in permafrost and the geotechnical considerations adopted for building on frozen soils. This study conducted a review of current practices in deep and shallow foundations used in northern Canada. The review summarized the current methods for estimating key factors, including the adfreeze strength, creep settlement, and frost heave, used in foundation design in permafrost. To understand the geotechnical considerations in foundation design, this study carried out interviews with several engineers or professionals experienced in designing foundations in permafrost; the findings and the interviewees’ opinions were summarized. Lastly, in order to demonstrate the design methods obtained from the interviews and review, the paper presents two design examples where screw piles and steel pipe piles were designed to support a residential building in northern Canada, according to the current principles for adfreeze strength, long term creep settlement, and frost heave. The permafrost was assumed to be at −1.5 °C, and the design life span was assumed to be 50 years. The design examples suggested that for an axial load of 75 kN, a 12-m-long steel pipe pile or a 7-m-long screw pile would be needed.

Keywords

• frozen soil
• foundations in permafrost
• pile design
• screw piles
• climate change