Enhancement of Pile-Soil Adfreeze Strength in Warming Permafrost

In this thesis, a research program aimed at developing a new retrofitting technique for enhancing bearing capacity of steel pile foundations in warming permafrost area is presented. The main goal was to refreeze the thawed soils surrounding pile foundations in permafrost regions and develop adfreeze bond at the pile-soil interface level by using a low temperature antifreeze circulated into steel pile. An experimental load test setup of a model steel pipe pile embedded in cohesionless ice-poor soils was carried out. The experimental results showed that local freezing is capable of developing adfreeze bond at the pile-soil interface. The pile shaft capacity significantly increased up to twice its initial shaft strength as a result of cooling application for only 25 min. An ABAQUS software model was also developed to investigate the effect of controlling parameters including pile diameter, thermal loads, and liquid circulation period on load carrying capacity of the piles.