A novel bond model based on three-dimensional sphere discontinuous deformation analysis for simulating rockfall-flexible passive net interactions

This paper proposes a novel bond model based on three-dimensional sphere discontinuous deformation analysis (SDDA) to simulate rockfall-flexible passive net interactions. At first, submatrices of the bond model added to the simultaneous equilibrium equations are derived. Then the relationship between elastic coefficient and spring stiffness for avoiding parameter calibration is built. And a failure criterion for breaking the bond between every two connected spheres is established. Four numerical tests are conducted to simulate the deformation and failure of a flexible passive net under the actions of forces and rockfall. The correctness, accuracy, and feasibility of the proposed bond model are verified by comparing the results with analytical solutions. Further, parameter sensitivity analysis is performed to investigate the influence of the anti-bending coefficient on computational stability and convergence, and to determine its reasonable value range. Finally, a simulation of flexible passive nets intercepting rockfalls on a mountain is carried out. Numerical performances show that the proposed bond model enables SDDA to properly simulate rockfall-flexible passive net interactions, providing a practical tool for rockfall mitigation in geotechnical engineering.