路堤荷载下水泥土桩复合地基沉降理论计算

基于路堤荷载下桩土非等应变条件和考虑了桩土相互作用、桩间土竖向与径向位移、桩土侧面产生相对滑移以及桩侧产生负摩阻力等特点的复合地基桩间土竖向变形模式,推导了水泥土桩复合地基桩间土沉降的理论计算公式,并以桩土单元体范围内的桩间土平均沉降值作为复合地基沉降,进一步推导了水泥土桩复合地基总沉降量、下卧层压缩变形量的理论计算表达式(两者之差即为加固区压缩变形量)。理论分析表明,复合地基加固区压缩量小于同深度天然地基压缩量,复合地基下卧层压缩量小于天然地基下卧层压缩量,复合地基总沉降量小于天然地基总沉降量。同时,理论计算结果与有限元计算结果以及现场实测结果三者比较一致。

Theoretical Calculation of Settlement of Soil-cement Pile Composite Ground under Embankment

Based on the unequal strain condition between the pile and the pile-surrounding soil,and the new pile-surrounding soil settlement model which considers the characteristics of interaction between the pile and the soil,the vertical and radial displacement of the pile-surrounding soil,the relative sliding between the pile and the soil,and the negative friction of the pile side in the soil-cement composite ground under embankment,the formulas for the pile-surrounding soil settlement in composite ground under embankment were derived.Taking the average settlement of the pile-surrounding soil in pile-soil unit as settlement of composite ground,the formulas for the total settlement and the compressive deformation of the underlying stratum in the soil-cement composite ground were further derived(the difference is just the compressive deformation of stabilized layer).Theoretical analyses indicate that the compressive deformation of stabilized layer of composite ground is smaller than that of nature ground in same depth,the compressive deformation of the underlying stratum of composite ground is smaller than that of nature ground,and the total compressive deformation of composite ground is smaller than that of nature ground.Meanwhile, theory results conform to that from finite element method and field measurement.