We investigated the strength and deformation characteristics of undisturbed unsaturated loess under different moisture content conditions. The results showed that the deviatoric stress intensity increases with the increase of confining pressure at the same moisture content and decreases with increasing moisture content at the same confining pressure. Moreover, the matric suction and the shear strength of unsaturated loess gradually decrease as the moisture content increases. It was found that cohesion in unsaturated loess is significantly larger than that in saturated soil. Under the same moisture content, the volumetric strain decreases as the axial strain increases, but this effect is less significant as the confining pressure increases. Moreover, at the same confining pressure, the volumetric strain increases with the moisture content. Based on the theory of unsaturated soil strength, the increasing gradient of cohesion, internal friction angle, and the relationship between the shear strength and the matric suction of the corresponding soil layers were obtained. These findings provide a reliable theoretical basis for the optimal design of tunnel linings, the selection of appropriate construction methods, and the evaluation of the stability of tunnel soils during construction.

我们研究了不同含水量条件下原状黄土的强度和变形特性。结果表明，在相同含水量下，偏应力强度随围压的增加而增加，在相同含水量下，偏应力强度随含水量的增加而减小。此外，随着水分含量的增加，非饱和黄土的基质吸力和抗剪强度逐渐降低。研究发现，非饱和黄土的内聚力明显大于饱和土。在相同的水分含量下，体积应变随着轴向应变的增加而减小，但是随着围压的增加，这种影响变得不那么明显。此外，在相同的围压下，体积应变随水分含量的增加而增加。基于非饱和土强度理论，得到了相应土层的内聚力梯度，内摩擦角的增大以及抗剪强度与基体吸力的关系。这些发现为隧道衬砌的优化设计，合适的施工方法的选择以及施工期间隧道土的稳定性评估提供了可靠的理论基础。