With the aim of modelling the energy dissipation phenomenon during the initiation and propagation of cracks, a novel cohesive fracture model is proposed in this study based on the multi-scale model of rocks and the Lennard-Jones potential between non-bonding molecules. The proposed model establishes the corresponding relationship of deformation in the multi-scale model of rocks and suggests that the fracture energy is essentially the manifestation of the transformation of deformation energy into potential energy between molecules. First, the multi-scale model of rocks is established based on the structural characteristics and fracture characteristics of rocks, and the corresponding relation of deformation at different scales is analysed. Thereafter, the force and potential energy equations of the cohesive fracture model corresponding to the tensile and shear processes are established. Finally, the accuracy of the cohesive fracture model is verified through three numerical simulations. The results indicate that the cohesive fracture model can accurately fit the theoretical values and experimental results in the Mode-I and Mode-II tests. In the uniaxial compression test, the cohesive fracture model can accurately simulate the uniaxial compressive strength and fracture pattern of rocks.

为了模拟裂纹萌生和扩展过程中的能量耗散现象，基于岩石的多尺度模型和非键分子之间的Lennard-Jones势，提出了一种新的内聚断裂模型。所提出的模型建立了岩石多尺度模型中变形的对应关系，并认为断裂能本质上是分子之间将变形能转化为势能的体现。首先，根据岩石的结构特征和断裂特征，建立了岩石的多尺度模型，并分析了不同尺度下的变形对应关系。之后，建立了与拉伸和剪切过程相对应的内聚断裂模型的力和势能方程。最后，通过三个数值模拟验证了粘性断裂模型的准确性。结果表明，内聚断裂模型可以正确拟合理论值和实验结果，在模式一和模式二的测试。在单轴压缩试验中，内聚破裂模型可以准确地模拟岩石的单轴压缩强度和破裂模式。