桩柱式高桥墩桩基稳定性分析

基于桩柱式高桥墩桩基与一般桩基的差异,以及高桥墩桩基中桩、柱和土体共同工作的原理,建立了将桩和柱视为一个整体的分析计算模型。假设桩侧摩阻力随土层变化均匀分布,并假定桩侧土体地基反力系数随深度线性增加,由能量法得到了考虑高桥墩桩基中桩、柱材料和几何特性差异的桩土体系总势能,利用势能驻值原理导出相应的屈曲临界荷载和稳定计算长度。计算结果表明,通过改善土体性质,可提高桩柱式高桥墩桩基的稳定性能,但在柱桩刚度比较大,埋深较小时,其效果是有限的;高桥墩桩基的无量纲稳定计算长度随桩埋深的增加而增大;桩柱式高桥墩桩基可能存在一最优的柱桩刚度比,此时柱、桩、土三者共同作用体系最为协调。经与有限元数值分析结果比较发现,两者吻合很好。

Stability Analysis of Pile Foundation with Higher Pile-column Bridge Piers

Based on difference between pile foundation with higher pilecolumn bridge piers and normal pile foundation,by using the interaction of pile,pier and soil,a pile-column calculation model was founded.Supposing the lateral friction distributed uniformly with soil layer and horizontal foundation coefficient of soil increased linearly by depth,the total potential energy of the pile-soil system was gained by using energy method considering material property and geometry property of pile and column in pile foundation with higher pile-column bridge piers.And buckling critical load and stability calculation length were derived by theory of conservation of potential energy.Numeric computed results show that(1)stability of pile foundation with higher pile-column bridge piers can be enhanced by improving the character of soil,while the stiffness ratio of pile and column is bigger and embedding ratio of pile is less,the effect of stability is limit;(2)the dimensionless stability calculation length increases with increases of embedding length of pile;(3)there maybe exists an optimal stiffness ratio of pile and column in pile foundation with higher pile-column bridge piers for the column-pile-soil system works in phase.The calculated results agreed well with the numerical results by finite element program.