This study proposes a new two-dimensional finite-discrete element method (FDEM) using dynamically inserted cohesive elements. Unlike the conventional FDEM, which sets up cohesive elements between adjacent solid elements to simulate fracture and fragmentation in the geomaterials, the new FDEM adaptively inserts the cohesive elements when the stress exceeds a critical value. The new method is consistent with the conventional FDEM except that it uses a post-peak constitutive model for cohesive elements and a new nodal updating scheme. The accuracy and efficiency of the new method are verified through a continuum mechanics example with an analytical solution. Examples of Brazilian disc and triaxial compression tests are used to verify the performance of this new method in simulating fracturing in geomaterials. Finally, dynamic loading on the Brazilian disc by a split Hopkinson pressure bar (SHPB) system is simulated, confirming that the new method effectively simulates dynamic fracturing problems. The study shows that computational results of the conventional FDEM highly depend on the penalty parameters of the cohesive elements. The adaptive FDEM overcomes these limitations with improved accuracy and efficiency by using adaptively inserted cohesive elements.

本研究提出了一种新的二维有限离散元方法 (FDEM)，该方法使用动态插入的粘性元素。与传统的 FDEM 在相邻实体元素之间设置粘性元素以模拟岩土材料中的断裂和碎裂不同，新的 FDEM 会在应力超过临界值时自适应地插入粘性元素。新方法与传统的 FDEM 一致，只是它使用了粘性元素的峰后本构模型和新的节点更新方案。通过连续介质力学验证了新方法的准确性和效率解析解的例子。巴西圆盘和三轴压缩试验的例子被用来验证这种新方法在模拟岩土材料破裂方面的性能。最后，模拟了分离式霍普金森压力杆(SHPB) 系统对巴西圆盘的动态加载，证实了新方法可以有效地模拟动态压裂问题。研究表明，传统 FDEM 的计算结果高度依赖于粘性单元的惩罚参数。自适应 FDEM 通过使用自适应插入的粘性元素克服了这些限制，提高了精度和效率。