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采用空心圆柱扭剪仪对杭州软黏土进行一系列不排水试验,首先求得软黏土的弹性参数,在此基础上研究主应力轴旋转条件下土体的非共轴特性,并探讨中主应力系数、弹性应变、偏应力水平和次生各向异性对非共轴特性的影响。试验结果表明软黏土的非共轴特性虽与砂土存在相似之处却又不尽相同。主应力轴旋转条件下,无论原状黏土还是重塑黏土,其非共轴角均随主应力方向角增加而循环波动变化,且周期约为90°;非共轴角基本随中主应力系数的增加而减小;弹性应变对加载起始时刻的非共轴角影响较大,如果忽略弹性应变的影响,将高估土体的非共轴特性;偏应力水平对非共轴角的大小和发展趋势均存在一定的影响,且偏应力水平越大,非共轴角越小。重塑土的试验表明,软黏土的非共轴特性并不完全由土体的初始各向异性所决定,次生各向异性的影响也很大。
A series of undrained tests were carried out on the soft clay in Hangzhou with a hollow cylindrical torsional shear instrument. The elastic parameters of the soft clay were obtained firstly. Based on this, the non-coaxial behavior of the soil under the rotation of the principal stress axis was studied, Effect of Coefficient, Elastic Strain, Deviation Stress Level and Secondary Anisotropy on Noncoaxial Property. The experimental results show that the non-coaxial properties of soft clay are different from those of sand. Under the condition of principal stress axis rotation, both non-coherent and remolded clays, the non-co-axial angles all fluctuate cyclically with the increase of the principal stress direction angle, and the period is about 90 °. Increase and decrease; the elastic strain has a great influence on the non-coaxial angle at the moment of loading; if the influence of elastic strain is neglected, it will overestimate the non-coaxial property of soil; Development trend has a certain impact, and the greater the partial stress level, the smaller the non-coaxial angle. Experiments on remolded soil show that the non-coaxial nature of soft clay is not completely determined by the initial anisotropy of soil, and the secondary anisotropy is also greatly affected.