Investigation of Warming Effects on Creep Behavior of Pile Foundations in a Frozen Sandy Soil Using Laboratory-Scale Tests

Climate change has resulted in accelerated permafrost thawing, which wreaks havoc on infrastructure in the Arctic such as pipelines, buildings, and roads. The thawing permafrost can have remarkable impacts on the mechanical behavior (e.g., bearing capacity and settlement) of pile foundations supporting Arctic infrastructure. This study was carried out to investigate the effect of warming on the behavior of pile foundations in frozen soils by performing axial loading and creep tests of model piles in a frozen soil-pile interaction lab at Clarkson University. A soil box of 1.38 m in length, 0.90 m in width, and 1.22 m in height has been built in a cold room. The air temperature in the cold room can be regulated from −50°C to 75°C to produce temperature cycles or freeze-thaw cycles of the soils using a programmable temperature control system. A model pile was installed in the soil box with a diameter of 63.5 mm, and length of 81.0 cm. In this study, axial load capacity and creep test were conducted to evaluate the behavior of the pile installed in frozen sandy soil. The axial load capacity of the model pile was 87 kN based on the quick test. Creep settlements of the pile subjected to a constant load of 10 kN were measured as the temperature of the frozen soil gradually increased from −8.20°C to −0.15°C to simulate the effects of warming. The creep rate was 0.007 mm/day when the temperature changed from −8.0°C to −1.0°C, but progressively increased to 1.787 mm/day at −0.20°C. This observation is presented in detail in this paper and underscores the importance of understanding pile foundation behavior in response to rising soil temperatures.