Hydrodynamic Characteristics of the Formation Processes for Non-Homogeneous Debris-Flow

Non-homogeneous debris flows are characterized by a wide grain size gradation, high volumetric weight and sediments not uniformly distributed along the vertical direction of the flow depth. These flows usually occur in the southwestern mountainous area of China during the rainy season, causing tangible and non-tangible damages; therefore, it is crucial to study their dynamic characteristics. An experimental campaign was conducted to replicate three processes typical of debris flows: (i) formation; (ii) propagation; and (iii) accumulation. Different flow rates, soil composition and flume slopes were applied. Multiple experimental parameters were quantified for each test conducted such as pore water pressure and velocity and a series of regression analyses were used to determine the relative impact of each experimental variable on these recorded parameters. The results showed that the flowrate and the vertical grading coefficient associated with the soil composition have the maximum and the minimum influence on the formation of debris flows and propagation velocities measured, respectively. This result is significant and needs to be considered when planning or designing control measures to reduce the impacts of debris flows.