Intercepting and impact resistance property of dry particle flow by PFC3D-based slit dam

Slit dams, as effective open barrier structures, are widely used to intercept granular flows. To investigate the blocking efficiency and impact force magnitude of slit dams, physical experiments are conducted to calibrate numerical simulation tests. In this study, a flume model without lateral confinement is established, and various slit dam configurations are designed to evaluate the effects of pillar spacing, number of pillar rows, and pillar staggering on the blocking efficiency and impact load of granular flows. The results indicate that all three factors are closely related to granular flow blocking and impact forces. (1) The pillar spacing is inversely proportional to the blocking efficiency and impact peak value; as the blocking efficiency decreases, the impact peak value and static passive earth pressure also decrease accordingly. (2) Increasing the number of rows reduces the blocking efficiency and impact force of the first row of slit dams. Compared to a single row of pillars, a double row of pillars reduces the impact force by 3.20%, while a triple row of pillars reduces the impact force by 2.39% compared to a double row. The impact peak value and passive earth pressure on the side pillars increase due to the dispersed granular flow. (3) The staggered pillar structure reduces the blocking efficiency of the first row of slit dams while simultaneously lowering the impact peak value of the front row. The staggered structure can reduce the impact peak value by 1.22%. (4) The experimental results laterally demonstrate that the multi-structural arrangement of slit dams increases particle collisions within the dam body, reducing the impact on the first row of dams and causing some particles to move forward. These findings provide a technical basis for the optimized design of open slit dams, enabling them to exhibit higher performance during the design phase.