Research On The Tensile Bearing Properties Of Auger Cast-In-Place Piles

Nowadays, more and more uplift loading piles are being put into work for buildings whichmay suffer lateral loads or uplift load such as the action of earthquake, wind and ocean wave etc.Our knowledge about tensile bearing properties of piles is relatively insufficient in contrast withthat of bearing properties of compressive piles. Many factors such as soil properties, pilediameter and length etc. may influence the working state of tensile piles. So, it is significant toresearch the tensile bearing properties of piles in different ground site conditions and differentpile models.In this paper, the research situation of tensile piles is summarized firstly, and then boththe factors influencing the utmost bearing capacity of tension piles and the methods to decidethe utmost bearing capacity are introduced systematically. On the basis of former study on therock-embedded piles, the double-folded line style is put forward to describe the load-transfer ofpile-soil interaction. Furthermore, by using the load-transfer methods, the influence of workingpoint of up-loadings on the side-friction is analyzed in theory, and then some reasonable adviceis provided for design and construction.Relying on the project of Auger Cast-In-Place Piles, USA-E, the static up-loading test iscarried out and the loading-up-displacement curve is got. On the other hand, the distribution ofaxial force and skin friction on different depths of the pile are obtained by the steel straingauges fixed in the pile beforehand. These first-hand data offer us a very good base to learn themechanical performance of tensile piles.Using Flac3D, the up-loading test of tension piles are simulated and calculated. Thesimulated loading-displacement curve and side-resistance curve generally accord with those gotin test and it shows the validity of Flac3D in simulating the mechanic performance of tensionpiles. Further, some material properties of piles and soils are analyzed in influencing the utmostbearing capacity and the up-displacements of tension piles. Some valuable learning aboutinfluential discipline of the factors on the stress and deformation mechanism of tension piles issummarized.