非共轴性是颗粒材料的重要变形特征。本书采用空心圆柱扭剪仪对Portaway砂及Leighton Buzzard砂进行排水试验，第一系列试验试件排水固结后沿着固定的主应力方向进行加载，另两个系列试验试件在排水固结后分别在偏应力值固定和增加的同时旋转主应力轴。试验验证了粗颗粒砂土主应力和主应变增量的非共轴特性，并得到不同因素对于非共轴性的影响规律。

本书内容包括：文献综述，试验方法介绍，单调加载试验，单纯旋转试验，结合加载路径试验以及研究结论。

本书读者包括岩土工程的研究者、设计者和建设者，以及对岩土工程研究感兴趣的人士。

The non-coaxiality between the major principal stress and the principal strain increment directions is found to be an important feature of granular materials.A hollow cylinder apparatus is used to investigate the non-coaxiality between the axes of the major principal stress and principal strain increment and the effects of different facters on the degree of non-coaxiality.In the first series of tests,the sand was isotropically consolidated before being sheared with the fixed principal stress direction.In the other two series of tests,the sand specimens were isotropically consolidated and then sheared by rotating the principal stress axes while the deviator stress level was either fixed (pure stress rotation) or increased continuously (combined shear loading).The evidence of non-coaxiality has been obtained from the tests.The degree of non-coaxiality is affected by the density of the specimen,the stress path followed,the stress level and the material particle properties.

The main content of this book includes literature review,experimental methodology,monotonic loading tests,pure rotation tests,combined loading tests,summary and conclusions.

The book's main audiences are the researchers,designers and constructers engaged in geotechnical engineering,as well as readers interested in the study of geotechnical engineering.