The mechanical properties of rock masses are significantly affected by the deformated behaviors of discontinuities, such as joints and faults. Rock masses in nature are also often subjected to dynamic disturbances, including explosive and seismic loads. Therefore, it is crucial to understand the deformed response of rock joints under dynamic loads. In this study, a series of dynamic compression expriments are carried out on rock joints with different joint roughness using the SHPB equipment with digital image correlation (DIC) technique. It found the dynamic compressive bebaviors of rock joints have viscoelstic features. Then a variable-order fractional Kelvin-Voigt (VFKV) model is proposed to simulate this behaviour, which consists of a variable-order fractional viscous dashpot and a spring in parallel. The model is verified to effectively represent the dynamic compressive process of rock joints. Finally, based the proposed model, the influence of model parameters, loading rate, and joint contact area ratio on the viscoelastic behaviour and mechanical property of rock joints are discussed. The results show the viscoelasticity behaviour of joints is significantly affected by the loading rate and joint contact area ratio, high loading rate and joint contact area may strengthen the elastic properties of the joints, while the joint roughness has the opposite effect.

岩体的力学性质受到不连续面变形行为的显着影响，例如节理和断层。自然界中的岩体也经常受到动态干扰，包括爆炸和地震载荷。因此，了解动态荷载作用下岩石节理的变形响应至关重要。本研究利用数字图像相关（DIC）技术的SHPB设备对不同节理粗糙度的岩石节理进行了一系列动态压缩实验。发现岩石节理的动态压缩行为具有粘弹性特征。然后提出了一个变阶分数Kelvin-Voigt（VFKV）模型来模拟这种行为，该模型由一个变阶分数粘性缓冲器和一个并联的弹簧组成。验证该模型能有效地表示岩石节理的动态压缩过程。最后，基于所提出的模型，模型参数、加载速率和关节接触面积比对讨论了岩石节理的粘弹性行为和力学性能。结果表明，加载速率和接头接触面积比显着影响接头的粘弹性行为，高加载速率和接头接触面积可能会增强接头的弹性性能，而接头粗糙度则相反。