挤扩支盘灌注桩承载力影响因素的数值模拟研究

Numerical Simulation and Research on the Factors that Affect the Bearing Capacity of Squeezed Branch Pouring Piles

运用PLAXIS有限元软件,基于岩土弹塑性本构关系的数值计算理论,建立桩-土轴对称模型,模拟支盘形状、位置、大小、数量和距离软弱层高度等参数条件下的桩基承载力特性及变化规律,分析在竖向荷载作用下挤扩支盘灌注桩对桩基承载力的主要影响因素。研究结果表明:支盘形状对于承载力没有明显影响;桩基承载力随支盘位置向下移动而逐渐提高,但是当支盘距桩底部距离小于L/3(L为桩长)时,支盘位置下移对桩基承载力影响不显著;桩基极限承载力随着支盘半径和支盘数量的增加逐渐提高;当支盘与软弱层间距小于4倍夹层厚度时,桩基承载力随支盘与软弱层距离的逼近而逐渐降低。研究结果可为挤扩支盘桩的设计参数选取提供参考,为支盘灌注桩的工程设计和优化提供技术支持。

Based on the numerical calculation theory of elastic-plastic constitutive relation of rock and soil,the pile-soil axisymmetric model is established by using the PLAXIS finite element software.The load characteristics and rules of pile foundations under the influence of parameters such as the shape,position,size,quantity and distance from the soft interlayer are simulated,and the main factors that influence the load characteristics of the squeezed branch pouring pile under vertical loads are analyzed.The study results show that:the shapes of bearing plate have no obvious influence on the load characteristics;when the distance between pile foundation and branch plate pile is larger than L/3(Lis the length of pile),the bearing capacity of pile foundation gradually increases with the downward movement of branch plate position,while when the distance is less than L/3,the downward movement of branch plate position has no significant influence on the bearing capacity of pile foundation;the ultimate bearing capacity of pile foundation increases with the increase of branch plates’radius or quantity.The results can provide valuable reference for parameters selections in the excavation branch designing and provide technical support for the design and optimization of branch pouring piles.