蒋德松 张承富 赵明华 杨超炜

摘   要：针对“路堤-加筋垫层-复合桩基”共同作用模型所存在的不足，从土拱、筋材变形以及桩土荷载传递三个方面对其进行改进.首先，考虑地基分层、埋深与上覆荷载对桩土荷载传递的影响，推导桩、土竖向变形函数.然后，引入沉降主控的筋材拉膜效应经验模型，考虑路堤与地基侧向变形对筋材拉力的影响.最后，在土柱模型的基础上，考虑相对位移量对界面摩阻力发挥的影响，推导路堤底部荷载分配与差异沉降的关系.在上述工作的基础上，以桩土沉降与荷载分配为等量关系，建立了改进后的路堤、筋材、桩体、桩间土共同作用模型，并得到了路堤下桩网复合地基的桩土应力比计算方法.通过工程实例对本文方法进行验证，证明了本文方法的合理性.

关键词：桩网复合地基;土拱效应;沉降;荷载传递;桩土应力比

中图分类号：TU470                        文献标志码：A

文章编号：1674—2974（2019）09—0123—10

Abstract： This paper focused on the improvement of the current pile-supported embankment calculation model from three aspects： soil arching effect，geotextile deformation and pile-soil load transfer due to the deficiency of the embankment- reinforcement- composite pile foundation interaction model. Firstly，considering the influence of foundation stratification， buried depth and overlying load on pile-soil load transfer，the vertical deformation function of pile and soil was derived. Secondly， the empirical model of the membrane effect was introduced to analyze the influence of the lateral deformation of the embankment and the foundation on the tensile force of the geotextile. Finally， based on the soil column model， this paper analyzed the relationship between load distribution and differential settlement at the bottom of the embankment in consideration of the influence of relative displacement on the interface friction. On the basis of the above work， the improved model of embankment， geotextile， pile and inter-pile soil interaction was established on the premise of the equal relationship between pile-soil settlement and load distribution，from which the calculation method was deduced of pile-soil stress ratio of pile-net composite foundation under the embankment. The rationality of the method mentioned was validated by practicable engineering examples.

Key words： pile-net composite foundation;soil arch effect;embankments;load transfer;pile-soil stress ratio

近年来，随着城际高铁的新建，铁路软基的问题日益突出，路基稳定性差、承载力不足、总沉降过大、非均匀沉降等问题尤为严重. 桩网复合地基因其造价低廉、施工速度快，能有效地减小路堤沉降及不均匀沉降的特点，进而得到广泛的应用. 同时，理论计算，特别是桩土应力比计算方法，取得了长足发展.

目前的桩土相互作用分析方法均是建立在以差异沉降控制荷载分配的基础之上.何宁等[1]、俞缙等[2]假定桩侧摩阻力呈线性分布，而陈仁朋等[3]、吕伟华等[4]假定……