桩与桩侧土之间的非线性滑移破坏的数值分析

根据桩与桩侧土的非线性剪切特征，采用接触单元来模拟桩与桩侧土之间的非线性滑移破坏，运用虚位移原理推导了桩-土三维等厚度接触元的单元刚度矩阵，较好地模拟桩与桩侧土之间的非线性滑移破坏。既考虑了剪力的传递，又考虑了相对位移，同时也研究了桩长、桩体弹性模量和桩径对桩轴力分布的变化规律的影响。通过实例计算，分析得到一些有益的结果：增加桩长可减少桩的端阻力；对于短桩，提高桩体弹模，虽然能提高桩体刚度，但对提高桩端阻力的影响较小；而对于超长桩，增大桩体弹性模量能增大桩轴力；不管短桩还是长桩，随着桩径的增加，桩轴力都在减少．实例表明，采用适当的桩长、桩径可充分发挥桩的作用。同时也表明了该方法的有效性和正确性。

Numerical analysis of non-liner slipping destruction of piles and surrounding soil of piles

The element stiffness matrix of pile soil three dimensional constant thickness contact interface element that can simulate process between piles and their surrounding under vertical loads is obtained according to non liner shear feature of surrounding soil of piles by applying theory of virtual displacement. This method considers the translocation of shears and relative displacement; also studies the variety for length, an elastic mold, and diameter of pile to distribute with axial force of pile regulation. By analysing and calculating examples, some satisfactory solutions are obtained: the increase in length can reduce the point resistanceof the pile; for the short pile, the increase in the elastic mold and stiffness develops fewer influences, but for super long pile,to enlarge an elastic mold can enlarge an axial force of pile; whether short pile or long pile, along with the increment of diameter of pile, the point resistance of pile all is decreasing; examples show the appropriate length and diameter of pile can well develop a pile's functions, also can express that method with accuracy.