考虑桩-土滑移的柔性基础下复合地基沉降分析方法  

Settlement Calculation Method for Composite Ground Considering Pile-soil Slip Under Flexible Foundation

作　　者：曹文贵[1] 王江营[1] 罗忠涛[1] 翟友成[1] 

机构地区：[1]湖南大学岩土工程研究所,湖南长沙410082

出　　处：《中国公路学报》2012年第6期9-16,共8页China Journal of Highway and Transport

基　　金：国家自然科学基金项目(51078137);教育部高等学校博士学科点专项科研基金项目(20090161110005)

摘　　要：为了考虑柔性基础下复合地基桩-土相对滑移特性和桩间土竖向应力变化对其沉降计算的影响,在分析复合地基沉降变形机理基础上,根据桩-土界面剪切变形特性,假定桩-土界面剪应力和剪切相对位移关系服从理想弹塑性模型,并将复合地基沉降视为由塑性区、弹性区和下卧层压缩变形区3个部分组成;根据塑性区桩-土界面剪应力与相对位移的关系特性,通过分析桩与桩间土竖向应力,建立塑性区压缩量分析方法;针对桩间土竖向应力变化特征,在对现有桩间土竖向位移模式进行改进的基础上,建立了考虑桩间土竖向应力变化和桩-土相对位移的弹性区压缩量计算模型,并采用已有复合地基下卧层压缩量分析方法计算下卧层的压缩量,从而建立柔性基础下复合地基沉降计算新方法。研究结果表明:该方法可反映桩-土相对滑移和桩间土竖向应力变化对沉降的影响;通过工程实例计算与其他同类方法进行对比分析,表明该方法合理、可行。To study the effect of pile-soil relative slip characteristics and vertical stress variation of soil between piles on the settlement calculation for composite ground under flexible foundation,based on the analysis of settlement mechanism of composite ground and shear deformation characteristics on pile-soil interface,the relationship between shear stress and shear displacement was assumed to obey the ideal elastic-plastic model,and the settlement was regarded as three parts： elastic zone,plastic zone and underlying stratum.According to the relationship between shear stress and relative displacement on the pile-soil interface,compression calculation method for plastic zone was established by mechanical analysis of the vertical stress between pile and soil.Aimed at the characteristics of soil vertical stress variation,and based on the improved vertical displacement model between soil and piles,a compression calculation model for elastic zone with consideration of both soil vertical stress variation and pile-soil relative slip was established,and the compression of underlying stratum was calculated by the existed method.As the result,a new settlement calculation method for composite ground under flexible foundation was proposed.The results show that this method can reflect the effects of relative slip and vertical stress variation on settlement.Practical engineering calculation and comparison with other methods indicate that this method is reasonable and feasible.

关 键 词：道路工程 复合地基 理论分析 柔性基础 沉降 桩-土相对滑移 

分 类 号：U416.1[交通运输工程—道路与铁道工程]