非比例循环加载条件下砂土的变形特性

采用香港科技大学的空心圆柱扭剪仪对砂土进行了剪应力幅值和应力主轴耦合循环变化的非比例加载排水试验.试验控制条件为:在剪应力幅值周期性变化的同时应力主轴相对试样的沉积方向在0°~180°之间循环旋转.着重分析了这一复杂非比例循环加载条件下砂土的变形特性,包括3个正应变分量的发展、剪应力剪应变关系以及体应变随循环周数的变化关系.其中体应变的主要规律为:随循环周数的增加,砂土的体缩应变不断累积,但累积速率呈递减趋势.试验同时发现剪应力幅值的变化幅度对砂土的变形特性有显著影响.

Deformation behavior of sands under cyclic non-proportional loadings

Drained tests for non-proportional loadings involving with cyclic variations of the deviatoric stress and principal stress axes were conducted on sands with a hollow cylinder apparatus at Hong Kong University of Science and Technology. The test condition was controlled to be that principal stress axes rotated cyclically from 0° to 180° to the vertical axis accompanied by the variation of the deviatoric stress simultaneously. The developments of three normal strain components and the volumetric strain with the number of cycles and the relationship between the shear stress and the shear strain components were analyzed in detail. With the increase of the cycle number, the contractive volumetric strain of sands induced is increasing, yet its increase rate is lowered. And it is found that the magnitude variation of the deviatoric stress plays a significant role in the deformation behavior of sands under cyclic non-proportional loadings.