软基路堤拓宽对原路堤桩体受力特性的影响

目的 交通量日趋饱和与建设用地日益紧张促使道路需要进行拓宽改建，为了进一步研究路堤拓宽时的稳定性，对软基路堤拓宽时原路堤下桩体受力特性的变化进行分析。 方法 采用Abaqus对离心机模型验证后，分别建立拓宽路堤与原路堤有限元三维数值模型进行对比分析，研究拓宽路堤自重、不同拓宽路堤土体参数对原路堤下不同位置桩体的受力和变形性状以及破坏模式的影响。 结果 数值仿真结果表明：路堤下各桩对抗滑的贡献不同，接近坡脚的桩主要受弯剪作用，远离坡脚的桩主要受轴力作用；拓宽路堤土体自重使得原路堤下桩体所受弯矩及剪力减小，所受轴力增大，越靠近拓宽路堤的桩受影响越大，原路堤下桩体的位移增大，其中靠近原坡脚处的竖向位移增量最大，横向位移增量最大处位于原路堤中部；拓宽路堤土体重度能显著影响原路堤的竖向位移，而其变形模量和强度参数对原路堤的竖向位移影响不明显；路堤拓宽后在荷载作用下，原路堤下桩体的受力特性较拓宽前会发生改变，潜在破坏模式由弯剪区、压弯区和受压区三个分区变为压弯区和受压区。 结论 所建模型能较好验证离心机试验结果，研究结果能对路堤拓宽的稳定性分析提供指导。

Effect of Soft Foundation Embankment Widening on Mechanical Characteristics of Piles in the Original Embankment

Introduction   The increasing traffic and the increasingly tight construction cause the roads to be widened and rebuilt. In order to further study the stability of the embankment, the change of the mechanical characteristics of the pile under the original embankment is analyzed when the soft foundation embankment is widened.      Method     After verifying the centrifuge model,a three-dimensional numerical model of the widened embankment and the original embankment was established using Abaqus. Based on the comparative analysis, the influence of gravity, deformation modulus, strength parameters of widened embankment on the mechanical characteristics, deformation behavior and failure mode were carried out.      Result     The numerical simulation results show that the piles under the embankment had different contributions to anti-sliding. The piles close to the slope are mainly subjected to bending and shearing, and the piles far away from the slope are mainly affected by the axial force. The weight of the widened embankment affects the mechanical characteristics of the pile in the original embankment: the main performance is that the bending moment and shearing for piles in the original embankment reduced, and the axial force increased; the displacement of piles in the original embankment increased, in which the vertical displacement increment near the original slope foot is the largest and the largest lateral one is located in the middle of the original embankment. The soil weight of the widened embankment significantly affects the vertical displacement of the original embankment, but its deformation modulus and strength parameters almost have no obvious effect. After the embankment is widened, the mechanical characteristics of the pile in the original embankment change under the load. The potential failure mode is changed from bending-shear zone, bending zone and compression zone to bending zone and compression zone.      Conclusion     The model can verify the centrifuge test results, and the results can provide guidance for the stability analysis of embankment widening.