Movement and impact-pressure characteristics of small dry granular landslide debris flow in natural gas pipeline crossing areas

To protect the safety of natural gas pipelines in landslide debris flow (LDF)–prone areas, a 3D model is developed based on discrete element method (DEM). By comparing with experimental data, the relative error is within ±10%. Firstly, the kinematic evolution of LDF is analysed, it can be found that the maximum average velocity is 6.3 m/s, the runout distance of the centroid of LDF is 36 m, the peak tangential average impact pressure is 7.24 × 103 Pa under the condition with slope length of 30 m, slope angle of 38°, a debris volume of 84 m3, and particle radii of 0.006–0.21 m. Secondly, the influence of different parameters on the motion parameters and mechanical properties of LDF on slope surface and flat runout zone is discussed. The results indicate that the main factors affecting the average impact pressure of LDF are the slope angle of the mountain and the volume of LDF. Finally, a prediction correlation for the maximum movement distance and average impact pressure of LDF is obtained based on nonlinear regression. This study provides theoretical support for the safety design of natural gas pipeline routes in mountainous areas.