基于无单元Galerkin法的软土区高承台超长嵌岩基桩屈曲分析

为探讨洞庭湖软土区桥梁工程常用高承台超长嵌岩灌注桩的屈曲稳定性,将其视为第二类稳定问题,引入新型无单元Galerkin数值分析法,考虑桩-土共同工作中的非变形协调与非线性等因素,给出了基于非线性弹性-理想塑性模型的桩土接触分析非线性迭代算法及基于弧长法的桩身屈曲分析无单元Galerkin法,并开发出相应的计算程序。最后,结合某大桥一试桩现场载荷试验结果进行了应用,对比分析表明:基于桩身屈曲分析无单元Galerkin法获得的桩顶荷载-沉降曲线与实测曲线吻合较好,桩身失稳临界荷载与实测极限荷载的相对误差为5.6%,远优于按第一类问题的线性与非线性增量屈曲分析结果(其相对误差分别达37.0%和15.4%)。

BUCKLING ANALYSIS OF SUPER-LONG ROCK-SOCKETED FILLING PILES IN SOFT SOIL AREA BY ELEMENT FREE GALERKIN METHOD

In bridge engineering,super-long rock-socketed filling piles with high cap are widely used in soft soil area such as Dongting Lake.In order to investigate their buckling stability,the second stability theory and a newly developed numerical method,i.e.the element-free Galerkin method(EFGM),were adopted to consider the non-concordant deformation and the nonlinearity of the pile-soil interaction.Then,based on the nonlinear elastic-ideal plastic interface model,a nonlinear iterative arithmetic was proposed,and the program using arc length method was developed.At last,the present method was applied to analyzing a bridge test pile.A comparison with the loading test results showed that,the calculated pile top load-settlement curve agreed well with the measured one.The relative error between the calculated critical load and the measured ultimate load is only 5.6%,better than that by linear and nonlinear incremental buckling analysis(whose relative errors are 37.0% and 15.4% respectively) based on the first stability theory.