Movement Morphology and Mechanical Characteristics of Small Landslide Debris Flow

The structural damage of buried pipelines is caused by the strong impact and pressure of landslide debris flow (LDF), which in turn affects the integrity and function of a pipeline. To ensure the safety of natural gas buried pipelines in areas with frequent LDF, the morphology changes and mechanical characteristics of LDF are studied during its movement process, and relevant mechanical predictive models are established. Firstly, a numerical simulation model of LDF movement is established by using the discrete-element method (DEM). The model parameters were calibrated through experiment, and the error was within ±15%. Secondly, the morphology of LDF is discussed in the process of movement. The results showed that the morphology of LDF is semiellipsoidal. The top-view shape perpendicular to the slope surface presents as elliptical, and its axis length increases first and then decreases. Meanwhile, combined with the movement morphology of LDF, the mechanical characteristics were studied between LDF and mountain slope surface. After the LDF moves for 4 s, the pressure on the slope surface on the elliptical axes shows a parabola shape. In short, the pressure of LDF on the disaster area presents a semiellipsoidal distribution. Lastly, the prediction model for LDF average pressure was established on the disaster area through the data-fitting method. The error was within ±10% compared with the simulation results, which can meet the engineering requirements. This study can provide a theoretical basis for the laying of buried natural gas pipelines through LDF disaster areas.