The investigation on damage creep properties of rock under freeze-thaw conditions are essential for assessing the long-term stability of rock mass engineering in cold regions. This research analyzed the damage characteristics of rock under the coupled effect of freeze-thaw cycles and loading; the damage variable under the coupled effect of freeze-thaw cycles and loading was proposed. A damage creep constitutive model was developed, and the determination method for the model parameters was proposed. The rationality of the model was calibrated using test data, and the calculation results of the proposed model were compared with classical Nishihara model. Additionally, the research analyzed the variation of model parameters with the number of freeze-thaw cycles and discussed the damage creep mechanisms of rock under the coupled effect of freeze-thaw cycles and loading.

Strength characteristics of graded gravels are essential in the construction of roadway and railway substructures. Traditional constitutive models, primarily nonlinear elastic and plastic types, fall short in accurately capturing the strain-softening properties of such materials. To address this limitation, the current study introduces a statistical damage model designed to outline the stress-strain behavior of densely compacted graded gravels in transport infrastructures. Utilizing medium-sized triaxial tests, the model examines variations in strength and deformation parameters in relation to compaction levels and incorporates a unique damage-softening index (DSI) along with a threshold axial strain to improve accuracy. The study establishes that the DSI and threshold axial strain effectively regulate stress-strain relations in the postpeak segment, the model's statistical parameters and threshold axial strain can be precisely determined through the introduction of DSI, and the model closely aligns with experimental data across multiple compaction levels. These findings are especially relevant for engineering design in the context of roadway and railway construction and indicate potential for further refinement, such as the incorporation of loading rate considerations.

This article studied the biomechanical properties of salix root sampled from arid and semi-arid regions of China. The damage law of root in the process of stretching was analyzed by acoustic emission technique. The fractal dimension of root failure was calculated by digital image processing technology. The results show that salix root tensile strength and ultimate elongation decreases with the diameter increasing, while ultimate tensile resistance and diameter are positively correlated. Damage variable characterized by cumulative AE energy can not only help research the rule of root damage quantitatively, but also allows determining the critical elongation when root became inactive. The optimal mining depth values are proposed, which enable reduction of ground surface deformation, elimination of root system damage, protection of planting on ground surface and, thus, decrease of possibility of bench convergence.