THE RELATIONSHIP BETWEEN DEBRIS FLOW DENSITY AND PARTICLE SIZE PARAMETERS

Sediment concentration is a key parameter in characterizing debris flows. Given the challenges associated with direct observation of active debris flows in practical settings,this study proposes a method for estimating sediment concentration using particle size distribution data. The method is based on long-term monitoring data from Jiangjia Gully in Yunnan Province,covering the periods 2004-2007 and 1974-1975. The results indicate that the particle size composition of debris flows follows a scaling distribution: P(D)=KD^-μ=exp(-D/D_c). The parameters μ and D_c effectively represent the particle composition,where μ reflects the porosity of the soil and D_c indicates the overall range of particle sizes. The study demonstrates that sediment concentration ρ is correlated with the parameters μ and D_c,leading to the development of a corresponding calculation formula. This formula is not regionally restricted,as it relies solely on the particle composition of the debris flow,eliminating the need for predefined characteristic particle sizes and minimizing subjective bias. Given the sensitivity of μ and D_c to changes in particle composition,these parameters can also be used to characterize the evolutionary process of debris flows.