Riding out the Thaw

In the past, engineers have often tried to build stable structures on ice-rich permafrost by providing means to keep underlying soils frozen. In an era of global warming, however, such efforts may be futile where soils are already near thawing temperatures. If development in such areas is to occur, engineers will increasingly need to design structures that can accommodate a thawing world beneath them. The author relates his experience with his own home, built in 1953 over ice-rich warm permafrost and continuously occupied while the frozen soils thawed entirely from beneath its heated basement. Four feet of differential settlement (thaw subsidence) was experienced during this process, requiring repairs on several occasions. Following thawing, drainage and consolidation of the silt soils, the foundation was replaced in 1999 with a conventionally built basement that has remained stable for more than a decade. The author discusses design features and other conditions that allowed for the successful continued use of the structure despite the extreme distress of the supporting soils. Lessons learned and areas where additional research might be productive are discussed with the illustrative examples.