An improved grain-based numerical manifold method (NMM) is developed to investigate deformation and damage of intact rocks at the meso‑scale. The grain boundaries are embedded into the numerical manifold method using a random Voronoi tessellation technique to approximate the microstructure of rocks at the meso‑scale. To enhance efficiency, an improved contact loop updating algorithm is proposed, which only preserves the corners of polygonal blocks and deletes the rest of the loop boundary nodes, thus greatly reducing the number of loop nodes involved in contact retrieval. An interface contact model considering cohesion and tensile strength between rock grains is incorporated into the numerical manifold method to simulate fracturing. With the newly developed grain-based numerical manifold method, Brazilian tests and uniaxial compression tests are numerically simulated to validate failure pattern and macroscopic response against laboratory tests. Sensitivity analysis is conducted using the proposed model to further investigate the influence of different number of grains and different stiffness ratio on the macroscopic response of rocks. The results indicate that the improved grain-based numerical manifold method can be effectively used to study deformation, damage and fracturing of rocks at the meso‑scale.

开发了一种改进的基于颗粒的数值流形方法 (NMM) 来研究中尺度完整岩石的变形和损伤。使用随机 Voronoi 镶嵌技术将晶界嵌入到数值流形方法中，以在中尺度上近似岩石的微观结构。为了提高效率，提出了一种改进的接触回路更新算法，只保留多边形块的角点，删除其余的回路边界节点，从而大大减少了接触检索中涉及的回路节点数量。将考虑岩石颗粒间黏聚力和抗拉强度的界面接触模型结合到数值流形方法中来模拟压裂。使用新开发的基于颗粒的数值流形方法，巴西试验和单轴压缩试验进行了数值模拟，以根据实验室试验验证失效模式和宏观响应。使用所提出的模型进行敏感性分析，以进一步研究不同晶粒数和不同刚度比对岩石宏观响应的影响。结果表明，改进的基于颗粒的数值流形方法可以有效地用于研究岩石的中尺度变形、损伤和破裂。