| Traditionally,uplift load is applied at the top of the pile.With increasing of uplift load,side friction resistance is gradually played role from shallow to the deep.Under the affection of uplift force,the pile will shrink in radial direction because of Poisson Effect.This will reduce both contact pressure and frictional resistance between soil and pile.Besides,excessive tensile stress in pile body may cause concrete crack,resulting in steel exposed and corrosion,finally affecting uplift capacity and the service life.In this article,two-depth-uplift-pile,a uplift pile with new loading structure is proposed.In two-depth-uplift-pile,a large diameter steel bar which upper part is separated from the pile body is placed at the middle of pile to transfer uplift force to the lower part of pile.So,the frictional resistance will play a role at two depth under uplift load as well as decrease tensile stress of pile dramatically.(1)Combining with the data of field pullout test,this article studied displacement,shaft force and frictional resistance characters of uplift pile with load at pile top.(2)This article simply introduced fundamental principle of finite element analysis(FEA)and used FORTRAN to program generalized parabolic model.Then this program was connected to ABAQUS and used in FEA model.After that,this article also analyzed experiment results and FEA results,verified the validity of FEA model.(3)Using FEA model which established by ABAQUS,change the load condition to effect load to different depth of pile.This paper illuminated deformation behaviour and uplift property of pile under uplift force at different position.(4)Based on the study mentioned above,changing the force condition,let the uplift load act on the top and middle or top and lower middle section of pile with different proportion.This article analyzed the displacement,stress,strain,side-friction and shaft force character of two-depth-uplift-pile and studied its deformation behaviour and uplift property. |
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