中文摘要：

根据土样纵向应变较高时最大剪切应变场中清晰剪切带所处位置沿剪切带方向布置平直测线,获得6条测线上从剪切带萌生至微裂纹刚出现过程中主应变轴偏转角的分布及演变规律,并对其进行了统计。研究发现：当微裂纹刚出现时,测线上主应变轴偏转角的高峰和低谷对应于2条共轭剪切带的交汇处附近或剪切带上最大剪切应变的局部高值区附近;在土样中部,剪切带上主应变轴偏转角主要分布在-5°-5°;随着纵向应变的增加,剪切带上主应变轴偏转角的标准差先降低,后趋于稳定;对于发生顺时针剪切的剪切带,主应变轴偏转角的均值主要为负值,而对于发生逆时针剪切的剪切带,主应变轴偏转角的均值以正值为主。

英文摘要：

We arrange six monitoring straiqht lines according to positions of clear shear bands along shear bands in maximum shear strain fields,and conduct statistical analyses.Distributions and evolution of principal strain axis rotational angle at six monitoring lines from onsets of shear bands to occurrences of microcracks are obtained.It is found that when microcracks just occur,the maximum and minimum principal strain axis rotational angles at shear bands correspond to vicinities of the intersecting points of conjugate shear bands or the regions with higher maximum shear strains.Except for regions closer to ends of specimens,the principal strain axis rotational angles at shear bands are within the range of-5°to 5°.With an increase of the longitudinal strain,the standard deviations of the principal strain axis rotational angles first decrease and then reach a stable status.For clock-wise shear bands,the averaged principal strain axis rotational angles are basically negative,but not vice versa.