Study On Behavior Of Post-tensioned And Part-bonded Prestressed Uplift Cast-in-place Pile Based On ABAQUS

In recent years, anti-pull effect in the design is more and more attention with thedevelopment and utilization of underground space, especially in the shallow water areas.Uplift pile is generally used to solve this problem in design. Post-tensioned and part-bondedprestressed uplift cast-in-place pile is a new uplift pile which resists the pull force byprestressing force to reduce the tensile stress and displacement of pile and avoid cracking. Itcan ensure the bearing capacity of the pile, decrease the consumption of steel and reduceproject cost.Post-tensioned and part-bonded prestressed uplift cast-in-place pile is more complexpiles than ordinary prestressed piles. Combined with the bond strength test of prestressedsteel strand and cement paste, the reliability of the bond strength of the bonded part inpost-tensioned and part-bonded prestressed uplift cast-in-place pile is proved by using thenumerical finite element analysis software ABAQUS simulation. And the relationshipbetween the prestressed steel strand bond length and the diameter of steel stranded wirewith different tensile strength is obtained for the future engineering design. Secondly, inorder to study the behavior of the post-tensioned and part-bonded prestressed upliftcast-in-place pile, the model is built by the finite element analysis software ABAQUS, thebehavior is analyzed through the axial force of pile, friction of the pile side and the curve ofload-displacement which are obtained by the compare and analysis of prestressed pile underdifferent conditions. On this basis, a further analysis is made about the relationship betweenthe prestressed uplift pile and the Poisson effect, as well as the influence of ordinaryreinforced to the prestressed uplift pile. Through the above analysis, the conclusions are:1.The side friction of post-tensioned and part-bonded prestressed uplift cast-in-placepile increases from the top to the end of pile. The Stress point is in the end of the pile, sothe top of pile is firstly tensioned and cracked. But it can be avoided by increasing theprestress and the piles will have more integrity.2.Prestress can resist the influence of the "necking" caused by "the Poisson effect", andit is conducive to increase the uplift.3.The non-prestressed reinforcement can increase the loss of prestress, limit the frictioneffect of the lower pile side, and make the stress point more closed to the end of the pile,which may increase the tensile force of piles. Although it can reduce the displacement of the pile body, it cost a great amount of steel. Therefore, only prestressed reinforcement inpost-tensioned and part-bonded prestressed uplift cast-in-place pile will save more steel.