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

Abstract

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.

Numerical Simulation of Non-Homogeneous Viscous Debris-Flows Based on the Smoothed Particle Hydrodynamics (SPH) Method

“…Details regarding the experimental procedure conducted can be found in [6]. For this study, three slurries were testes with densities ρ = 1400 kg/m 3 ; ρ = 1500 kg/m 3 and ρ = 1600 kg/m 3 .…”

“…The first category mentioned, the viscous debris flow, is particularly widely distributed in the mountainous areas of the southwest of China. This particular debris flow is characterized by high viscosity, wide particle-size distributions and uneven velocity distributions [6]. The difficulty in describing its motion process is due to the fact that the viscous debris flow is classified as a heterogeneous, non-constant, and non-Newtonian flow [7].…”

“…Experimental equipment for debris flow simulation[6].The experimental configurations chosen to examine the influence of vertical grading patterns on the debris flow formation and propagation are displayed inFigure 2.…”

Advances in Modelling and Prediction on the Impact of Human Activities and Extreme Events on Environments

“…Due to a rise in sea levels, which are expected to increase by between 0.07 and 0.12 m during the 21st century [18], communities living near coastal areas are facing potential multi-hazard threats. Furthermore, due to the increased extreme rainfall events, both urban and rural catchments are subject to continuous risks of flooding [19], where properties can be inundated and, in combination with the critical events and geographical characteristics such as steep slopes and proximity of houses near mountainous rivers, human losses caused by the landslides and debris flows can be escalated [20][21][22][23][24]. About 3.8 million km 2 and 790 million people in the world are living in relatively high exposure to at least two hazards, while about 0.5 million km 2 and 105 million people to three or more hazards (e.g., floods, droughts, tropical storms, earthquakes, volcanoes, and landslides), according to a report of the World Bank on the main hotspots of natural hazards [25].…”

Numerical Modeling of Debris Flows Induced by Dam-Break Using the Smoothed Particle Hydrodynamics (SPH) Method

“…Debris flows are among the most recurrent and damaging geological phenomena in mountainous areas across the world and have consistently caused loss of life, agricultural land, infrastructure, and buildings. China is the country affected by the majority of debris flows events and it has the most serious impact to date [1]. According to Zhang et al [2], 10927 debris flow disasters have been recorded in 23 provinces and cities between 2005 and 2015, with a direct economic loss of 14.2 billion Chinese Yuan.…”