In order to study the bearing capacity and load transfer mechanism of railway bridge pile foundation under vertical load in permafrost regions,the high pile cap foundation widely existing in permafrost regions is taken as the research object.The influence of pile foundation geometry size and permafrost temperature on the vertical bearing capacity of pile foundation is analyzed through a combination of indoor scale model testing and finite element modelling.The results indicate that increasing the length of the piles can effectively reduce the settlement and enhance the ultimate bearing capacity of the pile foundation.Specifically,for every 0.5 m increase in pile length,there is a corresponding increase in ultimate bearing capacity of the pile foundation by 41％,23％,and 15％respectively,in the process of increasing pile length from 1.5 m to 3.0 m.Additionally,longer piles also lead to reduced end bearing capacity while having minimal impact on axial force distribution,pile stress,and side friction resistance within the pile foundation.The existence of permafrost significantly improves the bearing capacity of pile foundations,with side friction resistance playing a crucial role.The enhancement effect becomes more pronounced as the temperature of permafrost decreases.At the permafrost temperature of-5 ℃ and-9 ℃,the ultimate bearing capacity of pile foundations reaches 125.9 kN and 199.5 kN respectively,representing an increase by factors of 2.98 and 5.31 compared to thawed soil conditions.In permafrost,the maximum side friction resistance of pile foundations is approximately 300 kPa and 500 kPa respectively,which is about 2.1 times and 3.5 times higher than that in upper thawed soil layer.Notably,significant changes occur in axial force,side friction resistance and soil stress along the interface between the upper thawed soil layer and the permafrost layer.
关键词
桩基础/多年冻土/承载特性/缩尺模型/室内试验/有限元分析
Key words
Pile foundation/Permafrost/Bearing characteristics/Scale model/Indoor test/Finite element analysis
维普
万方数据