Analysis and research on the difference of design codes for vertical bearing capacity of pile foundation in cold regions

The design results of pile foundations based on different national codes are not identical owing to differences in the design and calculation of the vertical bearing capacity of frozen soil pile foundation, thus inconveniencing pile foundation designers involved in international projects. This paper summarises the distribution of large-scale projects and the selection of pile foundations in cold regions. Models of a frictional elastic system and a friction end-bearing rigid-elastic system were obtained based on the vertical force characteristics of pile foundations under climate change in cold region. Differences in the design and calculation methods of the vertical bearing capacity of the pile foundations and the determination methods of the vertical ultimate bearing capacity in construction, transportation, and power transmission engineering in cold regions of various countries were discussed, and the applicability of each design method under complicated conditions was proposed. The calculations of the end resistance, side resistance, negative friction and frost heaving force of pile foundations in different national codes were described, and the values of partial safety factor for resistance and factor of safety were discussed, and the basis for the selection is summarised for different engineering design parameters. The study is intended to provide essential normative guidance for designing the vertical bearing capacity for pile foundation engineering in cold regions.