高层建筑长短桩复合地基性状有限元分析

通过由长短桩复合地基处理高层建筑软弱地基的工程实例,利用有限元法分析了不同的上部结构刚度、长桩长度、长桩置换率、短桩置换率对长短桩复合地基的平均沉降、差异沉降、桩土应力比、桩土荷载分担比所产生的影响及规律。结果表明:上部结构刚度的变化对复合地基性状的影响是有限的;长桩长度在控制平均沉降,改变地基承载力和改善桩顶应力集中方面影响显著;长桩置换率存在一定的合理取值范围;短桩置换率的变化对桩土应力变形影响不大。分析结果能为长短桩复合地基进一步优化设计提供参考。

Finite Element Analysis of Characteristics of Composite Foundation with Long-short-piles under High-rise Building

A case of the long and short piles composite foundation in liquefied soil under a high-rise building was taken.By using the finite element method,the effects of upper stiffness,cushion thickness,long pile length,long pile replacement ratio,short pile replacement ratio,raft thickness on average settlement,differential settlement,pile-soil stress ratio,pile-soil load-sharing ratio of composite foundation with long-short-piles were discussed separately.The results show that the upper stiffness had a limited effect on composite foundation;cushion thickness had a significant effect on the force characteristics of pile-soil;Long pile length had a significant effect on controling average settlement,and improving foundation bearing capacity and stress concentration of the top of the pile.Long pile replacement ratio varied in a reasonable range;short pile replacement ratio had a little effect on the stress and deformation of pile-soil;Differential settlement could be reduced with raft thickness increment.These conclusions provided references for future optimum design.