路堤荷载下桩筏复合地基受力及沉降特性研究

摘要

依托实际工程，运用 Midas／GTS软件建立三维有限元模型，对路堤荷载下CFG 桩筏复合地基受力及沉降规律进行研究．结果表明，桩筏复合地基具有良好的加固效果，能有效地减小沉降，提高地基承载力．路基填筑过程中，地基沉降分为快速发展阶段、发展阶段和稳定阶段．沿路基横断面方向，桩筏复合地基桩顶、桩间土沉降及竖向应力变化规律基本一致，均在路堤中心处最大，向两侧坡脚处延伸沉降值逐渐减小．沿深度方向，桩体沉降变化较小、桩间土沉降变化较大，二者在一定深度处相交；桩身轴力呈先增加后减小的趋势；桩侧摩阻力近似呈“S”形分布；中性点位置约在桩顶以下5．3 m处．所得结论可为路堤荷载下桩筏复合地基的设计及施工提供一定的参考．%Based on the practical engineering,three dimensional numerical simulation model is es-tablished by using software Midas/GTS to study the stress and settlement of CFG pile-raft com-posite foundation under embankment load.The result shows that the reinforcement effect of pile-raft composite foundation is remarkable.It can reduce the settlement effectively and improve the foundation bearing capacity.In the filling process of subgrade,the settlement is divided into rapid development stage,development stage and stable stage.The changing rule of settlement and ver-tical stress on pile top is roughly identical to that on the soil between piles.It is big in the center and small at both ends along the cross section.With the increase of depth,the changing range of pile settlement is smaller while the changing range of soil between piles is larger,and the settle-ment of these two structures intersect at a certain depth.And the axial force of pile firstly increa-ses then decreases.The distribution of skin friction is almost"S"shaped.The position of neutral point is 5 .3 m away from pile top.The conclusion obtained can provide reference for the design and of CFG pile-raft composite foundation under embankment load.