冻土区静钻根植桩竖向承载特性数值模拟研究

Numerical Simulation Study on Vertical Bearing Characteristics of Static Drilling Grounding Pile in Frozen Soil Area

基于静钻根植桩结构特点,利用ABAQUS建立三维有限元模型,开展静钻根植桩在冻土区的桩基承载特性数值模拟研究,分析竖向荷载下桩基荷载传递机理,讨论桩周冻土温度、桩周水泥土厚度和水泥土黏聚力对竖向承载特性的影响。结果表明,水泥土外壳是桩基承载力的关键,其竖向应力变化复杂;水泥土扩大头底部竖向应力较顶部增大了43%左右;竹节上下部位会发生应力突变,水泥土外壳竹节凹陷处下部较上部应力平均增大27.5%。桩周冻土常温与负温条件下桩基承载特性具有一定差异;桩周水泥土厚度应介于100 mm到0.5倍预制芯桩桩径之间;水泥土黏聚力在300 MPa左右对桩基承载力最有利。

Based on the structural characteristics of static drilling grounding pile,the three-dimensional finite element model was established by ABAQUS to conduct numerical simulation research on the pile bearing characteristics of static drilling grounding pile in frozen soil area.The load transfer mechanism of pile foundation under the vertical load was analyzed,and the influence of frozen soil temperature,cement soil thickness and cement soil cohesion on the vertical bearing characteristics were discussed.The results show that the cement shell is the key to the bearing capacity of pile foundation,and the vertical stress change is complicated;The vertical stress at the bottom of the cement soil expansion head increases about 43%over the top;The stress at the lower surface increases by 27.5%over the upper part.There are certain differences in the bearing characteristics of pile foundations under normal and negative temperature conditions of frozen soil around piles;The thickness of cement soil around pile should be between 100 mm to 0.5 times the pile diameter of precast core pile;The cohesive force of about 300 MPa is most favorable to the bearing capacity of pile foundation.