Debris Flow Damage Assessment by Considering Debris Flow Direction and Direction Angle of Structure in South Korea

Abstract

Recently, human and property damages have often occurred due to various reasons—such as landslides, debris flow, and other sediment-related disasters—which are also caused by regional torrential rain resulting from climate change and reckless development of mountainous areas. Debris flows mainly occur in mountainous areas near urban living communities and often cause direct damages. In general, debris flows containing soil, rock fragments, and driftwood temporarily travel down to lower parts along with a mountain torrent. However, debris flows are also often reported to stream down from the point where a slope failure or a landslide occurs in a mountain directly to its lower parts. The impact of those debris flows is one of the main factors that cause serious damage to structures. To mitigate such damage of debris flows, a quantitative assessment of the impact force is thus required. Moreover, technologies to evaluate disaster prevention facilities and structures at disaster-prone regions are needed. This study developed two models to quantitatively analyze the damages caused by debris flows on structures: Type-1 model for calculating the impact force, which reflected the flow characteristics of debris flows and the Type-2 model, which calculated the impact force based on the topographical characteristics of mountainous regions. Using RAMMS a debris flow runoff model, the impact forces assessed through Type-1 and Type-2 models were compared to check reliability. Using the assessed impact forces, the damage ratio of the structures was calculated and the amount of damage caused by debris flows on the structures was ultimately assessed. The results showed that the Type-1 model overestimated the impact force by 10% and the Type-2 model by 4% for Mt. Umyeon in Seoul, compared to the RAMMS model. In addition, the Type-1 model overestimated the impact force by 3% and Type-2 by 2% for Mt. Majeok in Chuncheon, South Korea.

Development of Statistics-Based Estimation Model (SEM) for Landslide-Triggering Factors Using the Soil Physical Properties of the Landslide in Gneiss and Granite Areas of South Korea

“…In August of the same year, a heavy rainfall in Chuncheon that led to landslides on the upper part of natural slides at the road used for entrance to the Soyang River Multipurpose Dam resulted to destroying houses and caused 40 casualties. As shown in these cases, landslides in Korea are concentrated from July to September, when the summer season's typhoons and localized heavy rainfall frequently occur, costing numerous lives and assets [4].…”

Forecasting of Debris Flow Using Machine Learning-Based Adjusted Rainfall Information and RAMMS Model

“…C is the flow material with cohesive force, and S becomes 0 when N = 0, and U = 0. An increase in C increases the friction force, which increases shearing stress and weakens the debris flow or avalanche [26]. RAMMS employs a Voellmy-fluid friction model( 9).…”

Evolution Pattern of Tailings Flow from Dam Failure and the Buffering Effect of Debris Blocking Dams

“…This study investigated the effect of the impact during the evolution process of leaked tailings flow on its downstream constructs, and the exerting range of impact force is the region that the discharged sediments flow through. The impact force of leaked tailings flow on the downstream constructs is calculated using Equation 7through Equation 9 [27,[37][38][39][40]. Multiple factors, including the impact angle, flow rate and density of tailings flow, can affect the computational results by varying degrees [38][39][40].…”

“…The impact force of leaked tailings flow on the downstream constructs is calculated using Equation 7through Equation 9 [27,[37][38][39][40]. Multiple factors, including the impact angle, flow rate and density of tailings flow, can affect the computational results by varying degrees [38][39][40].…”