Study on the Formation and Initial Transport for Non-Homogeneous Debris Flow

Abstract

Non-homogeneous debris flows generally occur during the rainy seasons in Southwest China, and have received considerable attention in the literature. Regarding the complexity in debris flow dynamics, experimental approaches have proven to be effective in revealing the formative mechanism for debris flow, and quantifying the relations between the various influencing factors with debris-flow formation and subsequent transport processes. Therefore, a flume-based and experimental study was performed at the Debris Flow Observation and Research Station of Jiangjia Gully in Yunnan Province, to theoretically analyze favorable conditions for debris-flow formation and initial transport by selecting the median particle size d 50 , flow rate Q, vertical grading coefficient ψ, slopes S, and the initial soil water contents W as the five variables for investigation. To achieve this, an optimal combination of these variables was made through an orthogonal experimental design to determine their relative importance upon the occurrence and initial mobilization behavior of a debris flow and to further enhance our insight into debris-flow triggering and transport mechanisms.

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

“…There are three configurations: Figure 1a shows the first configuration, with coarse particles as a bottom layer and fine sediment positioned above them; Figure 1b shows the second configuration, with coarse particles distributed on top of fine grains as a bottom layer; Figure 1c shows the third configuration, a realistic configuration with the original sediments collected from the Jiangjiagou Valley distributed along the entire measurement area. The first and second configurations separating coarse and fine particles were selected based on the three principles of vertical depositing patterns (i.e., normal, inverse grading and mixed) reported in earlier studies [38]. Figure 1 also includes the relevant particle size distribution curves for the material selected.…”

“…The propagation velocity of debris flow is a very important parameter since it relates to hazard intensity. It is very difficult to estimate for debris flows for large grain-size distributions [38] and therefore it is significant to characterize the relationship between the type of debris flow and the corresponding velocity distribution in China, where large grain-size distributions are common. By identifying this relationship, local and national authorities could allocate resources to improve the monitoring of areas at risk and implement mitigation strategies [39] to reduce the impact of debris flows and prevent the catastrophic consequences [12,40].…”

Functional Relationship between Soil Slurry Transfer and Deposition in Urban Sewer Conduits

“…In terms of flow characteristics, when particles are transferred, the fluid and solid particles interact in a complex manner. Past research has relied on experiments [5], but it is challenging in experimental analyses to review the independent influence of each variable on transfer deposition. Moreover, soil slurry has a dynamic flow in the transfer process.…”

Determining the Precipitation Intensity Threshold of Debris Flood Occurrence

“…The hazards caused by debris floods are enhanced by their sudden occurrences. Therefore, understanding the processes of debris flood occurrences is necessary not only to obtain insights into the mechanisms of debris flood occurrences but also to predict and avoid hazards (Shu et al 2017;. Due to the complexity of the mechanism of these floods and their high speeds, laboratory methods are appropriate tools for studying debris flood initiation processes (Cogan and Gratchev 2019).…”