Highly efficient contact detection strategy of 3D discontinuous deformation analysis in continuous-discontinuous simulation

Contact detection is the most time-consuming stage in 3D discontinuous deformation analysis (3D-DDA) computation. Improving the efficiency of 3D-DDA is beneficial for its application in large-scale computing. In this study, aiming at the continuous-discontinuous simulation of 3D-DDA, a highly efficient contact detection strategy is proposed. Firstly, the global direct search (GDS) method is integrated into the 3D-DDA framework to address intricate contact scenarios. Subsequently, all geometric elements, including blocks, faces, edges, and vertices are divided into searchable and unsearchable parts. Contacts between unsearchable geometric elements would be directly inherited, while only searchable geometric elements are involved in contact detection. This strategy significantly reduces the number of geometric elements involved in contact detection, thereby markedly enhancing the computation efficiency. Several examples are adopted to demonstrate the accuracy and efficiency of the improved 3D-DDA method. The rock pillars with different mesh sizes are simulated under self-weight. The deformation and stress are consistent with the analytical results, and the smaller the mesh size, the higher the accuracy. The maximum speedup ratio is 38.46 for this case. Furthermore, the Brazilian splitting test on the discs with different flaws is conducted. The results show that the failure pattern of the samples is consistent with the results obtained by other methods and experiments, and the maximum speedup ratio is 266.73. Finally, a large-scale impact test is performed, and approximately 3.2 times enhanced efficiency is obtained. The proposed contact detection strategy significantly improves efficiency when the rock has not completely failed, which is more suitable for continuous-discontinuous simulation.