堆载条件下基桩负摩阻力的有限元分析

Finite Element Analysis of Negative Frictional Resistancefor Pile under Surface Load

为了研究堆载对基桩负摩阻力的影响,利用有限元软件建立桩土相互作用模型并进行分析。计算结果表明,在相同工况下持力层的压缩模量越大,桩身轴力增加,中性点位置更靠近桩端,但基桩的摩阻力分布相同。在堆载等级、堆载时间对负摩阻力和中性点位置的影响分析中发现:桩身轴力随堆载等级的增大而增大,但端承桩的中性点位置不发生改变,摩擦桩的中性点位置下移;堆载时间增长,桩身轴力增大,孔隙压力消散。施工顺序对负摩阻力的影响也很大,先堆载后桩载产生的负摩阻力最小,并且中性点位置距离桩端最远,反之负摩阻力最大,且中性点位置距离桩端最近。

The purpose of this paper is to study the influence of surface load on negative friction of foundation pile.The pile-soil interaction model was established by finite element software for analysis.The results show that an increased axial force is associated with an increase in compressive modulus of supporting layer,and the neutral point position is closer to stake end,but the distribution of negative friction of pile is the same.Influences of surface load and stacking time on negative friction and neutral point position are analysed.The axial force of pile body increases with the increase of surface load grade,neutral point position of end bearing pile does not change while that of friction pile moves down.It is also linked to a reduction of load on pore pressure and increase in loading time.The construction sequence also has a great influence on negative friction resistance,The negative friction caused by heap loading before pile head loading is the smallest and the neutral point is the shallowest,whereas the negative friction is the largest and the neutral point is the deepest.