黏土地基中新旧混合群桩承载和变形的非线性分析方法

Nonlinear analytical method for load-settlement behavior of pile group composed of new and old piles in clay

受沉桩效应的影响,天然饱和黏土地层中新设静压桩与场地既有旧桩的承载特性存在显著差异,导致新旧混合群桩基础与传统新建群桩基础呈现不同的承载特性。针对新桩和旧桩桩周土体的力学特性,分别研究了饱和黏土地层中新桩与旧桩的单桩沉降计算方法。在此基础上,考虑土体的成层性、桩土相互作用的非线性和群桩沉降中的遮拦效应,提出了饱和黏土地层中新旧混合群桩基础的荷载-沉降关系非线性分析方法。通过工程实例验证分析,对不同布置形式的群桩基础的承载特性与荷载-沉降关系进行了探讨。研究结果表明,文中提出的分析方法能够合理反映饱和黏土地层中新旧混合群桩基础的承载特性,并预测其荷载-沉降关系,可为实际工程中新旧混合群桩基础的设计提供参考。

Compared with the old piles,the bearing behaviour of new piles is significantly different due to the pilejacking influence in natural saturated clay. Accordingly,there are obvious differences in the bearing behaviour and load-settlement relationship between traditional pile groups and pile groups composed of new and old piles. The computation method of settlement of single new pile and single old pile was completed according to the mechanic properties of the saturated clay around it. On this basis,considering the effect of soil layering,the nonlinearity of pilesoil interaction and the shielding effect,a nonlinear analytical method for the load-settlement relationship of pile groups composed of new and old piles in saturated clay was proposed in this paper. Then,the theoretical solution was verified by engineering examples,and the bearing behaviour and load-settlement relationship of pile groups composed of new and old piles with different configurations were subsequently analyzed in detail. The results show that proposed method can properly predict the settlement of the pile group composed of new and old piles in saturated clay,and can be used as a reference for the design of pile group composed of new and old piles in practical engineering.