堆载作用下桩体弹性模量对负摩阻力性状的影响

Influences of elastic modulus of pile on negative skin friction behaviors under the surcharge load

简要分析了桩体弹性模量对于桩体负摩阻力特性的影响机制。低弹性模量桩身压缩是桩顶位移的主要组成部分。在这种情况下桩身压缩对桩的荷载传递影响很大。在复合地基中常用的低刚度桩的桩-土相互作用分析中应当考虑桩身压缩的影响。有限元分析表明,影响桩体负摩阻力特性的桩体弹性模量存在一个临界值,当桩体弹性模量大于此值时,可以忽略桩体弹性模量对桩体负摩阻力性状的影响;桩体弹性模量小于此值时,桩身压缩变形增大,会造成中性点位置上移,桩身中最大附加应力降低。这些变化随着桩体弹性模量的降低而加剧。

The influences of elastic module of pile on negative skin friction(NSF) is simply analysed.Elastic compression deformation of pile is a key component of displacement at pile top in low elastic module piles.The influences of elastic compression of pile on load-transferring are evident in such cases.For low elastic module piles which are often used in composite foundation,have to take compression deformation of piles into account in analysis of pile-soil interaction.Finite element analysis shows that elastic module of pile that affects NSF exists a critical value.Influences of elastic module of pile on NSF can be neglected when elastic module of pile is greater than the critical value.Compression deformation of pile body increases while elastic module of pile is lower than the critical value.It makes the neutral point in pile move up and the maximum additional stress in pile play down.These changes become more evident as lowering elastic module of pile.