为研究结构性对黄土强度特性和屈服应力及屈服吸力的影响，以兰州非饱和原状Q3黄土及其重塑土为研究对象，利用非饱和土四联直剪仪和改进型非饱和土三轴仪进行了一系列的非饱和土直剪和各向等压加载以及三轴收缩试验。试验结果表明：原状黄土及其重塑土的黏聚力和内摩擦角均随吸力的增加呈线性增长趋势，吸力越大，抗剪强度越高；Q3原状黄土具有较高的结构性，其抵抗外力破坏的能力较高，而重塑土土粒之间结构比较松散，因此，原状土的抗剪强度要高于重塑土，尤其在低吸力和高含水率情况下；定义了黏聚力结构参数 和内摩擦角结构参数 ，得到了黏聚力耦合值 和内摩擦角耦合值 随吸力变化的拟合公式，为实际工程抗剪强度指标的选取提供另一种尝试；原状黄土的屈服应力和屈服吸力均大于重塑土，在p-s平面上原状黄土的弹性区要大于重塑土；两种土的屈服应力之差随着吸力的增大而线性增大，屈服吸力趋近于一常数，受净平均应力的影响较小；试样屈服前，原状黄土较强的结构性导致其变形要小于重塑土，试样屈服后，两者变形差别不大。试验结果为进一步建立结构性模型提供了试验基础，也为黄土地区工程建设提供了参数依据。

To investigate the influence of structural properties on strength parameters, yielding stress and yielding suction of unsaturated Q3 loess, a series of unsaturated soil tests, including direct shear test, hydrostatic triaxial compression test and triaxial shrinkage test, is carried out on Lanzhou undisturbed and remolded Q3 loess, using four-alliance direct shear apparatus and improved triaxial shear apparatus. The results show that the cohesions and internal friction angles of undisturbed and remolded loess increase linearly with matric suction. The greater the matric suction, the greater the shear strength. Because the undisturbed Q3 loess has well-developed structures, it possesses a higher strength. Compared to the undisturbed loess, the bonds between the remolded loess particles are weaker, so that the remolded loess shows lower shear strength than undisturbed loess, especially at low matric suction and high water content. The cohesion structural parameter and internal friction angle structural parameter are defined, and the variations of the coupling values of both cohesion and internal friction angle with suction are determined, providing a new approach to selecting shear strength parameters of practical engineering projects. It is shown that both yielding stress and yielding suction of undisturbed loess are higher than that of remolded loess, and elastic area of undisturbed loess is larger than that of remolded loess in p-s plane. The difference between the yielding stresses of undisturbed and remolded loess increases linearly with the increase of the suction, and yielding suction approaches a constant, which is almost unaffected by net mean stress. Before yielding, due to intensive structural characteristics, the deformation of undisturbed loess is less significant than that of remolded loess; but after yielding, the deformations of both are similar. The test results provide the experimental foundation for the development of structural model and some guidelines for the engineering construction in loess area.