Numerical Study on the Breaking Process of the Seafloor Massive Sulfide Based on the FEM-SPH Adaptive Coupling Algorithm

The research on seafloor massive sulfide (SMS) started relatively late, and the results on its breaking process are few. However, the breaking process contains evaluation indexes of safe, efficient and low-disturbance mining, so it is necessary to study the breaking process of seafloor massive sulfide. At the same time, the finite element method is used in most existing researches, and the system will automatically delete the failure element from the system during the simulation of rock-breaking, resulting in the inability to accurately obtain the chip state in the breaking process. In addition, SPH meshless method has unique advantages in dealing with large deformations of rock-breaking, but it has the problems of difficultly in boundary processing and serious computational time. In view of this, a hybrid discretization method of finite element method and smooth particle hydrodynamics (SPH) is proposed in this paper. On this basis, numerical simulation of a single-pick cutting seafloor massive sulfide based on the FEM-SPH adaptive coupling algorithm is carried out. Through the research in this paper, the regularity of the fragmentation process of polymetallic sulfides is obtained: firstly, the breaking process of seafloor massive sulfide experiences four stages: cutting-in of the pick, evolution of the high-stress zone, formation of the dense core, and the chips' splash. Secondly, the three-dimensional forces on the pick change in fluctuation in the cutting process. Thirdly, the stress wave propagation is unbalanced and biased in the cutting process. Fourthly, the chips' splash mainly has three directions: jet flow towards the opposite direction of the cutter cutting, spluttering perpendicular to the cutting surface of the pick, and sliding along the cutting surface. Finally, the chip mass is positively correlated with the cutting time. In this paper, a simulation framework for rock-breaking is proposed, and its advantages have been effectively verified.