现浇X形桩复合地基负摩阻力特性有限元分析

为了研究现浇X形桩复合地基的工作机理，运用ABAQUS有限元软件建立了现浇X形桩复合地基桩侧负摩阻力特性三维数值计算模型，分析了相关影响因素，并对比分析了X形桩与圆形桩复合地基力学性能差异。研究结果表明:桩侧负摩阻力和中性点位置随着地基土的固结不断变化，并最终逐渐趋于各自的稳定值；桩侧摩阻力和桩身轴力的大小受竖向荷载、桩-土接触面性质的影响较大，而静止土压力系数对桩侧负摩阻力的影响较小；相同荷载作用下，垫层的弹性模量越大，或桩侧土的弹性模量越小，桩体分担的荷载越多。相同条件下，X形桩复合地基与等横截面积圆形桩相比桩侧负摩阻力较大，中性点位置相对较低，而复合地基的沉降则较小。

Finite Element Analysis of Characteristics of Negative Friction of Cast-in-place X-section Pile Composite Foundation

In order to study the working mechanism of cast-in-place X-section pile composite foundation, the 3D numerical model calculating the shaft negative friction was established by use of ABAQUS finite element software with the related influencing factors analyzed, and the mechanical performance of X-section pile and circular pile composite foundation were compared. The study results show that, the shaft negative friction and the position of neutral point keep changing with consolidation of foundation soil, and then gradually tend to the respective stable values; the shaft friction and the axial force are impacted by vertical load and properties of pile-soil interface largely, and the shaft negative friction by coefficient of static earth pressure less; under the action of same load, the larger the elastic modulus of cushion or the smaller the elastic modulus of soil around pile, the more load the pile shares; in the same conditions, X-section pile compared to circular pile with the same section area, is subject to larger shaft negative friction and lower position of neutral point, thus the composite foundation has less subsidence.