考虑高路堤土拱效应层状地基中带帽刚性桩复合地基的承载特性

Bearing Characteristic of Composite Foundation Reinforced by Rigid Pile with Cap in Layered Ground Considering Soil Arching Effect of High Embankment

为了给高路堤下带帽刚性桩复合地基提供设计依据,针对高路堤下带帽刚性桩复合地基荷载传递特点,将带帽桩和桩帽下部分土体视为复合桩体,同时假定复合桩体间土体的位移模式,并考虑高路堤填土的土拱效应和桩帽间土体的成层性,基于变形协调原理,建立了高路堤-复合桩体-桩帽间土体相互耦合的荷载传递模型,推导得到了高路堤荷载作用下带帽刚性桩复合地基的桩土应力比和桩土差异沉降计算公式,以工程实例验证了该计算方法的合理性,并分析了桩长、桩间土压缩模量、桩帽截面尺寸、桩间距等因素对桩土应力比的影响。研究结果表明:桩长、桩间土压缩模量和桩帽截面尺寸对桩土应力比影响显著,而桩间距、填土内摩擦角、填土黏聚力和填土压缩模量对桩土应力比影响较小。

To provide a design basis for the composite foundation reinforced by rigid pile with cap under high embankment,according to the load transfer characteristic of the composite foundation,the combination of pile with cap and a part of soil underlying it was idealized as a composite pile.At the same time,by supposing the displacement modes of soil between composite piles,and considering the layered property of soil between pile cap and soil arching effect of high embankment,a load transfer model accounting for high embankment-composite pile-soil intercoupling was set up in line with the principle of deformation compatibility.The formulas to compute pile-soil stress ratio and differential settlement between pile and soil of the foundation were derived respectively.Rationality of the proposed method was verified by actual engineering projects.The influences of factors such as length of pile,compression modules of soil between piles,dimension of pile cap,and piles spacing on pile-soil stress ratio were analyzed.The results show that length of pile,compression modulus of soil between piles,and dimension of pile cap have significant influence on pile-soil stress ratio,while piles spacing,internal friction angle offill,cohesion of fill,and compression modulus of fill have relatively little influence on pile-soil stress ratio.