基坑开挖致偏位的PHC桩承载力弹性地基梁有限元分析

FEM Analysis of PHC Piles With Excessive Lateral Displacements Using Winkler Foundation Model

在基坑开挖过程中,当PHC桩发生被动偏移,桩顶出现超过规范限值的横向变形后,桩顶承压时,桩身存在额外的弯矩和剪力,此时桩的抗压承载力可能由桩身的抗弯、受剪强度控制。本文以某软土场地的项目为例,基于弹性地基梁模型,对发生了被动偏移的PHC桩进行了有限元分析,研究桩偏位超过规范限值后的桩身内力分布模式和变形特点,论证桩的承载力情况,并结合现场条件和检测结果,指出当桩发生大于规范限值的被动偏位时,桩仍具有相当的竖向承载力,在工程上可以继续利用其承载力。

Excessive lateral displacements may occur along the upper parts of PHC piles,when unexpected soil deformations take place during pit excavations.The excessive lateral displacements lead to extra bending moment and shear force along the pile body,which may cause the failure of piles.A case study is presented to show how to use the winkle beam model to calculate the internal force and deformation of the piles with excessive lateral displacements.FEM analysis results and site tests show that piles with relatively large passive displacements can sustain relatively large loads and usable in some extend,even the displacementsare larger than the code permissions.