Study On Anti-frost Heaving Characteristics Of The Screw Piles In The Seasonal Frozen Region

In frozen region, buildings and constructions are always damaged in response to the frost heave and thaw settlement of foundation soil and how to prevent such damage has troubled engineers for a long time. As a new kind of pile, being promoted broadly at home and abroad, screw piles have been used in various engineering for decades. Especially, in recent years, it has been successfully applied in projects against larger uplift in non-frozen soil. Therefore, the study of frost heave and thaw settlement of foundation soil in seasonally frozen region and permafrost region is of great importance in theory and practice. In this paper, the finite element model for screw pile entity is built up on the platform of finite element analysis software ABAQUS. Moreover, the process of screw piles be lifted by frost in the seasonally frozen region is simulated. The impact of displacement variation vertically suffering frost heave, mechanical performance, deformation behavior of surrounding soil and geometric parameters on screw pile are also studied. The main study contents are listed as follows:Firstly, in order to highlight the remarkable performance on frost-resistant uplift, screw piles are compared with linear piles by numerical simulation. The results show that the former is superior to the latter on frost-resistant uplift capacity. Force-bearing features of pillar body, deformation behavior and scope of surrounding soil of screw piles are studied so as to find out its force mechanism under the action of frost heave.Secondly, the influence of different geometric parameters of screw piles under frost heaving condition is also simulated based on ABAQUS software. The size of the pitch which affects the pile-soil failure state significantly, and the inner-outer diameter ratio also plays a important factor on the frost-resistant uplift capacity of piles.Finally, the boundary value size of the screw pitch is obtained according to the theory of deep foundation from Meyerhof, which made the piles and soil in different failure states, and it is consistent with the simulation results. A formula is proposed to estimate the frost-resistant uplift bearing capacity of screw piles based on the results.