钉形搅拌桩复合地基荷载试验的三维数值模拟

3D numerical analysis on bearing tests of T-shaped cement-soil deep mixing column composite foundation

介绍了一种新型水泥土搅拌桩(钉形搅拌桩),并在现场荷载试验的基础上,对不同桩体本构模型、不同桩数、不同桩土界面处理的钉形搅拌桩复合地基荷载试验的数值模拟方案进行了对比分析,确定了合理的模拟方法.结果表明:对于可能发生桩身屈服的数值模拟,桩体采用线弹性模型是不合适的;只设一根加载单桩不能反映现场荷载试验的群桩工作状态;对于该工况,采用加接触面、加过渡层和无接触面等不同桩土界面处理的结果差别不大.利用三维数值模拟分析了钉形搅拌桩复合地基的荷载传递和变形特性:钉形搅拌桩桩身荷载主要集中在扩大头部分,且衰减较快,变截面处桩身轴力有较大衰减,扩大头桩侧摩阻力较大,下部桩体侧摩阻力较小;桩身变形集中在扩大头,桩间土变形则集中在变截面以下较短范围内.

A new cement-soil deep mixing column named T-shaped cement-soil deep mixing column is simply introduced. Based on bearing tests in test site, 3D numerical simulation on bearing tests of T-shaped cement-soil deep mixing column composite foundation with different column constitutive models, model sizes, column quantity, column-soil interface treat methods were conducted, the reasonable method was then determined after analysis and comparison. Some conclusions are drawn. It＇s not suitable to use elastic model for column in numerical simulation when column may become yielded; only setting a single loaded column can not reflect the column group working state; and there are little difference in simulation results, whether column-soil interface are treated with interface element, transition layer, or nothing for situation. The load transfer and settlement behavior from the simulation results are also analyzed： most of the column load concentrates on the enlarged column cap, and distributes quickly, there is more load attenuation at the variable section. The skin friction of enlarged column cap develops more adequately than underside column. The column settlement concentrates on enlarged column cap, and soil settlement concentrates on a little area below the variable section.