Study on the Relationship Between Particle Distribution Parameters of Debris Flow Deposits and Cohesion

Abstract Jiahe Gully, located in Jiahe Village, Zhonglu Township, Weixi County, Yunnan Province, has experienced numerous debris flows of varying scales, resulting in significant casualties and property damage. This study investigates the relationship between particle distribution parameters and the cohesion of debris flow deposits. By sampling different locations along the channel basin and conducting particle scaling analysis combined with strength experiments, a linear relationship between the particle distribution parameter ( μ ) and the cumulative percentage of particles below 2 mm ( P ( D 2)) was identified. It was found that the migration of fine particles in the source area, random cessation of materials upstream, and supplementation from tributaries contribute to the wavelike development of particle parameters ( μ and D c). The cohesion ( c ) was observed to increase linearly with μ, suggesting that fine particles significantly influence cohesion through cementation and electrostatic interactions. Conversely, the internal friction angle ( φ ) decreases as D c increases, indicating that coarse particles are crucial in its development. These findings highlight the importance of particle gradation in determining soil strength and provide a quantitative basis for understanding debris flow mechanisms. Further verification is needed to determine the applicability of these conclusions to other basins. Future research should also incorporate particle shape, soil dynamics, and permeation theory for a more comprehensive analysis.