群桩受扭工作性状及非线性计算理论研究

Bearing behaviors and nonlinear theory of pile groups subjected to torque

复杂环境或复杂结构下的群桩基础将受扭矩荷载作用,深入探讨受扭群桩工作性状,并建立相应计算理论十分必要。首先在分析受扭群桩变形与荷载分配特点的基础上,考虑实际工程中各基桩的刚度差异,提出采用3个参数(承台转心x坐标与y坐标、转角φ)描述各基桩位移量的方法,并基于力平衡条件解算承台转心位置及任意转角条件下各基桩所分配的水平荷载和扭矩荷载。引入p–y曲线法与单桩扭矩刚度计算理论分别确定各基桩的水平刚度与扭转刚度,考虑受扭群桩中基桩共同工作特性与扭矩–水平荷载耦合作用特性,结合现有的试验成果确定了相关计算参数的取值。根据该方法编制了相应的计算机程序,实例分析表明,本文程序计算结果与实测结果吻合较好。最后,对刚度不对称时群桩转心位置的偏移量进行了计算分析,获得了一些有益的结论。

The pile groups with complex structure or constructed in complex circumstances will be subjected to torque.It is of significance to study their bearing behaviors and to establish relevant calculation theory.According to the characteristic of rotation and load distribution in pile groups subjected to torque,an equation for determining the horizontal load and torque on each pile in the groups is established based on the force equilibrium conditions,and a method for determining twist center location of pile groups with asymmetrically horizontal rigidity distribution of piles is proposed.The coupling effect between piles and loads are analyzed based on recent researches.The method to calculate angle of twist of caps and loads distributed over each pile is obtained by introducing the p-y curve method and the torsion rigidity theory of a single pile.The relevant codes are programmed,and also employed to analyze centrifuge tests on a pile group,and the computed results are compared with the experimental results.The agreement is good.Finally,location offset of twist center of pile cap with asymmetrically horizontal rigidity distribution is analyzed,and some beneficial insights are provided.