This paper presents a systematical investigation on the mechanical behaviours of frozen subgrade soil under various stress paths. A series of triaxial compression tests under six typical linear stress paths were conducted on artificially saturated frozen samples at a temperature of −6.0 °C by using triaxial low-temperature apparatus (MTS-810). The effects of stress path on mechanical behaviours such as stress–strain (axial and volumetric strain) relationship, failure strength surface, initial stiffness, cohesion and friction angle of frozen sample were analysed and discussed, respectively. The experimental results show that the evolution law of volumetric strain, equivalent cohesion, friction angle and initial stiffness are significantly affected by the stress paths. The plastic deformation stages in stress–strain curves are influenced by the stress paths. The shape and size of experimental failure surface for frozen soil in deviator-mean stress space is not sensitive to the stress paths, but the mean stress at the peak point decreases with the increase of loading angle. Finally, a new nonlinear strength criterion, considering the stress path effect and ‘three stage’ distribution characteristics, is proposed to predict the experimental strength surface of frozen subgrade soil. This failure criterion is capable of giving a good description for the multiaxial failure characteristics of frozen soil in a wide range of loading angles.

本文对冻土路基在不同应力路径下的力学行为进行了系统的研究。使用三轴低温设备（MTS-810）在-6.0°C的温度下对饱和饱和冷冻样品进行了六个典型线性应力路径下的一系列三轴压缩测试。分别分析并讨论了应力路径对机械行为的影响，例如应力-应变（轴向和体积应变）关系，破坏强度表面，初始刚度，内聚力和摩擦角。实验结果表明，应力路径对体积应变，等效内聚力，摩擦角和初始刚度的演化规律有显着影响。应力-应变曲线中的塑性变形阶段受应力路径的影响。偏平均应力空间中冻土实验破坏面的形状和大小对应力路径不敏感，但峰值峰值处的平均应力随加载角的增加而减小。最后，考虑应力路径效应和“三阶段”分布特征，提出了一种新的非线性强度准则，以预测冻土路基的试验强度面。该破坏准则能够很好地描述冻土在大载荷角范围内的多轴破坏特性。但在峰值点处的平均应力随着载荷角的增加而减小。最后，考虑应力路径效应和“三阶段”分布特征，提出了一种新的非线性强度准则，以预测冻土路基的试验强度面。该破坏准则能够很好地描述冻土在大载荷角范围内的多轴破坏特性。但在峰值点处的平均应力随着载荷角的增加而减小。最后，考虑应力路径效应和“三阶段”分布特征，提出了一种新的非线性强度准则，以预测冻土路基的试验强度面。该破坏准则能够很好地描述冻土在大载荷角范围内的多轴破坏特性。