Model for Predicting the Anti-Frost-Jacking Capacity of a Belled Pile in Seasonally Frozen Soil Regions

In seasonally frozen soil regions, frost heave may result in frost jacking or the failure of piles, posing a potential threat to the structural integrity of upper constructions. The belled pile, which has an enlarged base, can be applied in such places to reduce this adverse effect. To predict the anti-frost-jacking capacity of belled piles, a model is proposed that is based on Mindlin’s solution and the principle of virtual work. The anti-frost-jacking capacity is characterized by the anchorage factor: the ratio between the anchorage force and the tangential frost heave force. Based on this model, we consider factors affecting the anti-frost-jacking capacity, including the tangential frost heave stress, the ratio of enlarged base diameter to pile diameter (D/d), the ratio of embedded depth to enlarged base diameter (L/D), and the bell angle. The results of the proposed model agree well with test data, thereby validating the model. The anchorage force of a belled pile increases linearly with tangential frost heave stress and exponentially with freezing depth. However, increasing the tangential frost heave stress has no effect on the anti-frost-jacking capacity at the same freezing depth. Moreover, increasing D/d or the bell angle while decreasing L/D can benefit the anti-frost-jacking capacity of a belled pile.