中文摘要：

在土体主应力方向的旋转过程中,主应力方向与塑性主应变增量方向之间存在着非共轴现象,非共轴现象对应力-应变关系具有显著的影响。通过有限元二次开发,将角点结构非共轴理论应用到有限元程序ABAQUS中；对密砂单剪试验进行数值模拟,研究了非共轴现象及其对应力-应变关系的影响；采用离心模型试验方法,对圆形浅基础作用下饱和密砂地基荷载-变形特性进行试验研究；对离心模型试验进行数值模拟,将试验结果与数值计算结果进行对比,对非共轴模型的计算结果的合理性进行验证。研究结果表明：非共轴现象对浅基础地基荷载-变形特性具有显著的影响；当选取合理的非共轴塑性模量时,非共轴模型的计算结果与离心模型试验结果比较接近。

英文摘要：

In the process of rotation of the orientation of principal stress,the non-coaxial phenomenon exists between the orientations of the principal stress and plastic strain rate.The non-coaxial phenomenon gives an important influence on the relationships between stress and strain.The yield vertex non-coaxial theory is implemented into the FEM software ABAQUS through the user subroutine,which is implemented into numerical simulations of simple shear test for dense sand to study the non-coaxial phenomenon and its influence on the stress-strain relationship.Secondly,the load-deformation characteristic of shallow foundations is studied based on the centrifuge modeling test with saturated dense sand.Finally,numerical simulations of centrifuge tests are carried out,and the numerical results are compared with centrifuge test results to validate the rationality of the non-coaxial model.The research results show that the non-coaxial phenomenon gives an important influence on the load-deformation characteristic of shallow foundations,and the non-coaxial model＇s calculation results are close to the centrifugal modeling tests＇ results when a reasonable non-coaxial plastic modulus is chosen.