双向耦合剪切条件下砂土的变形特性

Deformation Behavior of Sands Under Bi-directional Coupling Loading

采用空心圆柱扭剪仪对粉细砂进行一系列偏应力幅值和大主应力角同步增大条件下的剪切排水实验,研究该双向耦合条件下饱和砂土的变形规律和非共轴特性,分析中主应力系数等因素对砂土变形特性的影响。结果表明:砂土在该椭圆应力路径条件下产生了一定的塑性变形,并表现出明显的非共轴特性;随着中主应力系数的增大,土体径向应变和体应变逐渐减小,而环向应变由压应变逐渐转变为拉应变;初始偏应力和偏应力增长幅度对土体变形也有明显的影响,随着这两者的增大,土体的剪应变明显增大,体应变也呈现出由体胀向体缩转化的趋势,非共轴角则呈现减小的趋势。

A series of bi-directional loading drained experiments involving with variations of the deviatoric stress and principal stress axes were conducted on fine sands with a hollow cylinder apparatus.The deformation behavior and non-coaxiality of fine sands under elliptical stress path were studied.The effect of intermediate principal stress parameter,initial deviatoric stress and increment of deviatoric deformation behavior of sands were analyzed.The results show that the fine sands produce plastic deformation and non-coaxial behavior can be observed obviously under elliptical stress path.With the increase of intermediate principal stress parameter,the radial strain and volumetric strain reduce,and the circumferential strain changes from compressive strain to tensile strain gradually.With the increase of initial deviatoric stress and increment of deviatoric stress affecting soil deformation obviously,the shear strain increases obviously.The volumetric strain shows a tendency from expansion to shrinkage,and the non-coaxial angles show a decreasing trend.