排水条件下原状软黏土各向异性和非共轴特性试验研究

Experimental study of anisotropy and non-coaxiality behavior of natural clay by using drained shear test

目前针对黏土各向异性的试验研究大多是在不排水条件下进行的,排水条件下的研究较为缺乏。采用空心圆柱扭剪仪,在不同的中主应力系数b和大主应力方向角?下对温州原状软黏土进行定向排水剪切试验。试验结果表明:各向同性固结的软黏土,在不同的大主应力方向角下的应力–应变发展关系存在着明显差异;相比于不排水条件,排水条件下的土体应变发展较为平缓,应变急剧发展的拐点不明显;中主应力系数对于应变发展有明显影响,并且当中主应力系数处于[0.5,1.0]区间中此影响更加显著;在定向剪切过程中,黏土的非共轴特性与大主应力方向角?存在着明显的关系,在?=0°和90°时非共轴特性不明显,非共轴特性在?=45°处出现拐点。这些结论可加深对软黏土在排水条件下各向异性的理解,为建立更加合理的软黏土本构模型和指导工程设计提供一定的基础。

Recent studies on anisotropy of soft clay are mostly carried out under undrained condition. There is a lack of anisotropy study of soft clay under drained condition. By using hollow cylinder apparatus（HCA）, a series of drained shear tests were carried out, under different direction of principal stress and different intermediate principal stress coefficient. The results show that the isotropic consolidated soft clay has different stress-strain behaviors with different directions of principal stress. Compared to undrained condition, strain development is more gentle under drained condition and the inflection point of rapid strain development is not that obvious. Intermediate principal stress coefficient has a significant effect on strain development, especially when it lies in the range of [0.5, 1.0]. The non-coaxiality of soft clay turns out to highly depend on the direction of principal stress. The non-coaxiality is not remarkable when the direction of principal stress is around 0 ° or 90 °, and 45° is a inflection point for the non-coaxiality of soft clay. The conclusions made by this paper can help us have a betterunderstanding of the anisotropy of soft clay under drained condition, also provide a foundation for establishing constitutive relations and guiding engineering design.