Study on dynamic loading effects and disaster mitigation performance of open-type check dams

Open-type check dams are extensively employed to alleviate the impact of debris flow disasters in mountainous terrains. However, the mitigation performance of permeable barriers under coupled slurry and boulder movement remains insufficiently studied. Furthermore, designers often overlook the significant dynamic loading effects of debris flows, leading to insufficient structural safety margins and frequent damages. To address these issues, this paper investigates both the dynamic load effects (bending moments and shear forces) on open-type check dams and their mitigation performance. The study employs Euler beam theory to solve the structural dynamic response and a coupled SPH-DEM-FEM numerical method to simulate debris flow interaction with the dam. The results of the study indicate that the dynamic load effects significantly exceed static load effects. For open-type dams, impact forces manifest as sawtooth impulses dominated by the instantaneous impact of boulders, while close-type dams experience rectangular impulses dominated by slurry siltation pressure. Numerical simulations reveal that a relative opening size (opening size to maximum boulder diameter ratio) greater than or equal to 2 effectively prevents dam plugging across varying boulder contents (10%-30%). The research achievements provide a scientific basis for the design of open-type check dams, enhancing both structural safety and regulatory efficacy.