高层建筑长短桩复合地基性状有限元分析

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

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。

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 re placement ratio had a little effect on the stress and deformation of pile-soil; Differential settle ment could be reduced with raft thickness increment. These conclusions provided references for future optimum design.