<p>This study examines the interaction between granular flows and barrier systems in landslides, employing both a landslide model test and PFC^3D discrete element simulations. The investigation focuses on the temporal evolution of the granular flow front velocity and changes in flow states, with an emphasis on slope angles and lateral blockage ratios. The results demonstrate that the front velocity of granular flows exhibits a generally increasing trend. More pronounced acceleration occurs on steeper slopes with moderate blockage ratios, while lower slopes or higher blockage ratios lead to slower acceleration. Despite this, an overall increase in velocity is consistently observed across all scenarios. A critical transition is identified at the 0.2-s mark, where slope angle plays a pivotal role, and interactions with barriers cause the flow to split and deflect, resulting in energy dissipation. Furthermore, under controlled single-variable conditions, the study reveals that the average flow velocity is inversely proportional to the lateral blockage ratio and directly proportional to the slope angle. The barrier system significantly influences the flow velocity: for the first row of barriers, the total average velocity attenuation increases with steeper slopes and higher blockage ratios, while for the second row, the attenuation shows a proportional relationship with the lateral blockage ratio. These findings contribute to the understanding of granular flow dynamics in landslides, providing valuable insights for debris flow mitigation, landslide risk management, and engineering applications involving barrier systems.</p> Graphical Abstract <p></p>