考虑非共轴特性的吸力桶基础竖向荷载-变形特性研究

土体在剪切变形过程中会产生较为显著的主应力方向旋转,主应力方向与塑性主应变增量方向将呈现出显著的差异即非共轴现象.采用砂土非共轴弹塑性本构模型,以吸力式桶形基础为研究对象,研究土体主应力方向旋转和非共轴角度的变化规律,探讨非共轴特性对地基荷载-位移关系的影响.研究结果表明:在竖向荷载作用过程中,土体主应力方向处于单调旋转状态,吸力桶形基础高径比对土体主应力方向的旋转规律(方向、速率和极值)有显著影响.非共轴特性对荷载-位移关系的发展趋势有显著的减缓滞后作用,该作用在地基变形中期比较显著.随着高径比的增加,非共轴特性逐渐显著,该特性对地基竖向荷载-位移关系的影响逐渐明显.

Research on vertical load-deformation behavior of suction bucket foundations in consideration of non-coaxial characteristic

The directions of principal stress could rotate during the shearing process of soils, meanwhile, the difference between the directions of the principal stress and the plastic principal strain increment is obvious, which is called the non-coaxial phenomenon. In view of the suction buckets foundations, a non-coaxial constitutive model of soil is used to analyze the change rules of the rotations of the directions of the principal stress and the non-coaxial angles, and to study the non-coaxial influence to the relations of the load and the displacement of the foundation. The study results show that the directions of the principal stress rotate monotonously in the vertical loading process, and that the height-diameter ratio of the suction bucket foundations has obvious influence to the rotations rule of the principal stress directions at the aspects of the direction, speed and extreme value. The non-coaxial characteristic could slow down the development trend of the relations of the load and displacement, which is more obvious at the middle of the deformation process of the foundation. When the height-diameter ratio increases, the non-coaxial characteristic is more obvious and its influence to the vertical loading-displacement relations of the foundation is also more obvious.