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为研究主应力轴旋转情况下饱和软黏土的变形及强度特征,采用先进的空心圆柱扭剪仪(HCA)对软黏土进行了一系列不排水剪切试验。试验采用等压固结模式对软黏土空心薄壁试样进行固结,并在3种不同中主应力系数情况下,对试样进行不同主应力轴旋转角度下的不排水剪切试验;剪切过程中保持平均应力、中主应力系数及主应力轴旋转角度不变,只增加偏应力,研究不同中主应力系数情况下主应力轴旋转角度对软黏土应力应变特征以及强度特性的影响。研究结果表明:不同主应力轴旋转角度下天然软黏土的变形及强度特征存在明显的差异,在中主应力系数b=0.5的非轴对称加载情况下,不排水剪切强度随着主应力轴旋转角度的增大呈勺形变化;在b=0的轴对称压缩条件及b=1的轴对称拉伸条件下,随主应力轴旋转角度的增加,不排水剪切强度均呈递减趋势。
In order to study the deformation and strength characteristics of saturated soft clay under the rotation of principal stress axis, a series of undrained shear tests on soft clay were carried out by using advanced hollow cylinder shear tester (HCA). In the experiment, the isobaric consolidation mode was used to consolidate the hollow thin-walled samples with soft clay, and under the condition of three different middle principal stress coefficients, the specimens were subjected to undrained shear tests under different principal stress axis rotation angles. In the process of cutting, the average stress, the principal stress coefficient and the rotation angle of the principal stress axis are kept unchanged. Only the deviatoric stress is increased, and the influence of the principal stress axis rotation angle on the stress and strain characteristics and the strength characteristics of the soft clay under different medium principal stress coefficients is studied. The results show that the deformation and strength characteristics of natural soft clay under different principal stress axis rotation angles have obvious differences. Under non-axisymmetric loading with main stress coefficient b = 0.5, the undrained shear strength changes with the main stress axis Under the condition of axisymmetric compression with b = 0 and axisymmetric stretching with b = 1, the undrained shear strength decreases with the rotation angle of the principal stress axis increasing.