双层土体结构对超长桩承载性状的影响

Numerical study on behaviors of lengthy pile in two-layer soil

摘要: 利用三维有限元方法,研究了双层地基土中超长桩的承载性状.利用线弹性模型模拟桩身混凝土的应力应变关系.邓肯-张非线性弹性模型模拟地基土,河海大学薄单元模型模拟桩.土间的非连续变形.计算结果表明,对上硬下软地基土结构,当硬土层厚度不大于桩身人土深度时,随硬土层厚度的增大,桩顶极限荷载、桩侧极限阻力均呈非线性增大;对上软下硬地基土结构,当软土层厚度不大于桩身入土深度时,随软土层厚度的增大,桩顶极限荷载、桩侧极限阻力均呈非线性减小;桩身轴力和桩侧阻力沿深度的分布随地基土结构而异.桩侧摩阻力在硬、软土层分界处有急剧变化现象;超长桩的失稳由桩侧土体的破坏引起.

Abstract: Based on a 3-dimensional finite element method(3D FEM),the behaviors of lengthy pile in two-layer soil have been studied.The stress-strain relationships of pile concrete are simulated by a linear elastic model,and that of the soil is simulated by a nonlinear elastic model developed by Duncan and Chang.A special thin-layer element model developed by Hohai University is used to simulate the non-linear displacement between pile and soil.The calculated results show that,for the hard-soft two-layer soil structur...