现浇X型混凝土桩的荷载传递机理初探

Study on Load Transfer Mechanism of Cast-in-Place X-Shaped Piles

现浇X型混凝土桩技术是河海大学开发研制的用于地基加固处理的一项新技术。在模型试验的基础上,通过有限元方法研究了现浇X型混凝土桩的荷载传递机理,并与模型槽试验结果进行了对比,分析中考虑了桩和土之间的接触和土的非线性。通过数值分析,揭示了X型桩的截面形式对侧摩阻力分布、端阻力发挥的影响。计算结果表明,由于桩的泊松比效应,X型桩截面周边不同位置的侧阻力大小有所不同;X型桩中出现了类似于H型桩的"半封闭土塞",与圆截面桩相比,桩端附近的侧摩阻力有较明显的增加;X型桩的桩端承载力系数要小于圆截面桩的情况,体现了X型桩截面形状的影响。

The technology of cast-in-place X-shaped piles is an innovation developed by Hohai University for strengthening soils. Based on the full scale test, the load transfer mechanism of the X-shaped pile was studied by 3D nonlinear finite element analyses. In the analyses the interface elements were used to represent slippage and separation between the soil and the pile. The numerical results were compared with the results of the chamber tests. The difference of bearing behavior between an X-shaped pile and a round pile and the effect of the partial soil plug on shaft resistance and end resistance were studied. The results show that the skin friction varies along the perimeter of the pile＇s section due to the effect of Poisson＇s ratio. Similar to the H-shaped pile, there is also a partial soil plug in the X-shaped pile, and the skin friction near the pile base is larger than that of the round pile. The end bearing capacity factor of the X-shaped pile is found to be smaller than that of the round pile, which also reflects the effect of X-shaped section.