Numerical investigation on flexible barriers impacted by dry granular flows using DEM modeling

The interaction of flexible barriers and granular flows has two complex mechanical processes: the continuous large deformation of flexible barriers and the discrete motion of particles. Owing to the fact that the theoretical method for the interaction of flexible barriers and granular flows is immature, a DEM method is proposed. In this method, the Hertz-Mindlin bonding particle model is employed to simulate the flexible barriers. The no-slip Hertz-Mindlin model is used to simulate the granular flows. The flexible barrier with lateral anchorage cable is selected. The change rate of kinetic energy W_k and the ratio of the dead zone mass friction F_m to the total mass of the granular flows are defined to compare the dynamic impact response of flexible barriers to retaining wall. The results show that the impact of granular flows causes large horizontal deformation and vertical deformation of cables firstly. Then, the direction of impact load converts to the horizontal one, so that the horizontal deflection in the upper dead zone of cables and the horizontal accumulation range of granulars increase. The total normal force impacting on the retaining wall calculated by the empirical formula agrees with that of the numerical method. Based on the results of numerical simulation and theoretical calculation, the maximal total normal force impacting the flexible barrier calculated by the empirical formula is over 45% greater than the maximum total normal force calculated by numerical simulation. Therefore, it is needed to reappraise the relationship between dynamic pressure coefficient C_D and Froude number Fr before calculating the maximum normal force using the empirical formula.