• Title/Summary/Keyword: Debris Analysis

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Landslide Analysis Using the Wetting-Drying Process-Based Soil-Water Characteristic Curve and Field Monitoring Data (현장 함수비 모니터링과 습윤-건조 함수특성곡선을 이용한 산사태 취약성 분석)

  • Lee, Seong-Cheol;Hong, Moon-Hyun;Jeong, Sang-Seom
    • Journal of the Korean Geotechnical Society
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    • v.39 no.5
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    • pp.13-26
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    • 2023
  • This study examined the soil-water characteristic curve (SWCC), considering the volume change, using wetting curves on the field monitoring data of a wireless sensor network. Special attention was given to evaluating the landslide vulnerability by deriving a matric suction suitable for the actual site during the wetting process. Laboratory drying SWCC and shrinkage laboratory tests were used to perform the combined analysis of landslide and debris flow. The results showed that the safety factor of the wetting curve, considering the volume change of soil, was lower than that of the drying curve. As a result of numerical analyses of the debris flow simulation, more debris flow occurred in the wetting curve than in the drying curve. It was also found that the landslide analysis with the drying curve tends to overestimate the actual safety factor with the in situ wetting curve. Finally, it is confirmed that calculating the matric suction through SWCC considering the volume change is more appropriate and reasonable for the field landslide analysis.

Analysis of Erosion and Deposition by Debris-flow with LiDAR (지상 LiDAR를 이용한 토석류 발생에 의한 침식, 퇴적량 측정)

  • Jun, Byong-Hee;Jang, Chang-Deok;Kim, Nam-Gyun
    • Journal of the Korean Association of Geographic Information Studies
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    • v.13 no.2
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    • pp.54-63
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    • 2010
  • The intensive rainfall over 455 mm occurred between on 9 to 14 July 2009 triggered debris flows around the mountain area in Jecheon County. We mapped the debris flow area and estimated the debris flow volume using a high resolution digital elevation model (DEM) generated respectively from terrestrial LiDAR (Light Detection And Ranging) and topographic maps. For the LiDAR measurement, the terrestrial laser scanning system RIEGL LMS-Z390i which is equipped with GPS system and high-resolution digital camera were used. After the clipping and filtering, the point data generated by LiDAR scanning were overlapped with digital map and produced DEM after debris flow. The comparison between digital map and LiDAR scanning result showed the erosion and deposition volumes of about $17,586m^3$ and $7,520m^3$, respectively. The LiDAR data allowed comprehensive investigation of the morphological features present along the sliding surface and in the deposit areas.

A Study on the Inflow and Seasonal Characteristics of Foreign Marine Debris in the Coastal Area of the West Sea (서해안 일대 외국기인 해양쓰레기의 유입과 계절적 특성 연구)

  • Jang, Seon-Woong;Park, Jae-Moon;Chung, Yong-Hyun;Kim, Dae-Hyun;Yoon, Hong-Jo
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.15 no.2
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    • pp.89-100
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    • 2012
  • The aim of this study knows to occurrence characteristics and monthly transition of foreign marine debris by changing in the marine environment for the national marine debris monitoring areas in the west coastal area. The Jeju Island (5,112) had the highest number for foreign marine debris flowed in the coast. Many areas in the next were surveyed by Hajo Island (1,967), Imja Island (507). Plastic bottles were the most common type to 2,925 piece of the whole collection. Then, the monthly occurrence amount was concentrated in July, September. At this time, analysis results of the marine environment are as follows: The sea surface wind of southerly or southeasterly were predominated. In addition, the sea surface circulations were dominated by inflow of seawater southward along the China Coast and northward from the East China Sea.

Sensitivity Analyses for Maximum Heat Removal from Debris in the Lower Head

  • Kim, Yong-Hoon;Kune Y. Suh
    • Nuclear Engineering and Technology
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    • v.32 no.4
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    • pp.395-409
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    • 2000
  • Parametric studies were performed to assess the sensitivity in determining the maximum in-vessel heat removal capability from the core material relocated into the lower plenum of the reactor pressure vessel (RPV)during a core melt accident. A fraction of the sensible heat can be removed during the molten jet delivery from the core to the lower plenum, while the remaining sensible heat and the decay heat can be transported by rather complex mechanisms of the counter-current flow limitation (CCFL) and the critical heat flux (CHF)through the irregular, hemispherical gap that may be formed between the freezing oxidic debris and the overheated metallic RPV wall. It is shown that under the pressurized condition of 10MPa with the sensible heat loss being 50% for the reactors considered in this study, i.e. TMI-2, KORI-2 like, YGN-3&4 like and KNGR like reactors, the heat removal through the gap cooling mechanism was capable of ensuring the RPV integrity as much as 30% to 40% of the total core mass was relocated to the lower plenum. The sensitivity analysis indicated that the cooling rate of debris coupled with the sensible heat loss was a significant factor The newly proposed heat removal capability map (HRCM) clearly displays the critical factors in estimating the maximum heat removal from the debris in the lower plenum. This map can be used as a first-principle engineering tool to assess the RPV thermal integrity during a core melt accident. The predictive model also provided ith a reasonable explanation for the non-failure of the test vessel in the LAVA experiments performed at the Korea Atomic Energy Research Institute (KAERI), which apparently indicated a cooling effect of water ingression through the debris-to-vessel gap and the intra-debris pores and crevices.

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Analysis of Characteristics of some of Forest Environmental Factors on Debris Flow Occurrence - With a Pusan and Ulsan Metropolitan Areas - (토석류 유출에 기인하는 몇 가지 산림환경인자 분석 - 부산 및 울산광역시를 중심으로 -)

  • Lee, Hae-dong;Park, Jae-hyeon
    • Journal of Korean Society of Forest Science
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    • v.104 no.2
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    • pp.213-220
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    • 2015
  • This study was carried out to determine the distribution of factors as effected by debris flow in Ulsan and Pusan metropolitan areas because mainly debris flow caused by typhoons and local heavy rainfall events is mainly attributed to damage of human being ad property. The high risk degree of debris flow was to affected by east (20%), northeast (20%) and northwest (20%) slopes with stand age class with elevation (69%) of 100-200 (33%). Also, the risk was high in high erosion collapse degree with slope degree of $20-25^{\circ}$ with over 300 mm (100%) of maximum daily rainfall events and 50-100 mm (50%) or >100 mm (50%) of maximum hourly rainfall events with <5 km of stream path and <50 ha of catchment area. Landslide debris and wood residue flow was also related to igneous rocks (73%) and bank collapse types of debrs flow (57%).

The Study on the Extraction of the Distribution Potential Area of Debris Landform Using Fuzzy Set and Bayesian Predictive Discriminate Model (퍼지집합과 베이지안 확률 기법을 이용한 암설사면지형 분포지역 추출에 관한 연구)

  • Wi, Nun-Sol;JANG, Dong-Ho
    • Journal of The Geomorphological Association of Korea
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    • v.24 no.3
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    • pp.105-118
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    • 2017
  • The debris slope landforms which are existent in Korean mountains is generally on the steep slopes and mostly covered by vegetation, it is difficult to investigate the landform. Therefore a scientific method is required to come up with an effective field investigation plan. For this purpose, the use of Remote Sensing and GIS technologies for a spatial analysis is essential. This study has extracted the potential area of debrisslope landform formation using Fuzzy set and Bayesian Predictive Discriminate Model as mathematical data integration methods. The first step was to obtain information about debris locations and their related factors. This information was verified through field investigation and then used to build a database. In the second step, the map that zoning the study area based on the degree of debris formation possibility was generated using two modeling methods, and then cross validation technique was applied. In order to quantitatively analyze the accuracy of two modeling methods, the calculated potential rate of debrisformation within the study area was evaluated by plotting SRC(Success Rate Curve) and calculating AUC(Area Under the Curve). As a result, the prediction accuracy of Fuzzy set model wes 83.1% and Bayesian Predictive Discriminate Model wes 84.9%. It showed that two models are accurate and reliable and can contribute to efficient field investigation and debris landform management.

Development of Precast Concrete Method for Eco-Pillar Debris Barrier with Hollow Cross-Section (중공트랙형 단면의 프리캐스트 에코필라 사방댐 공법개발)

  • Kim, Hyun-Gi
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.3
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    • pp.542-552
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    • 2018
  • In this paper, the precast method of a concrete eco-pillar debris barrier was proposed to improve the construct ability and economic efficiency. The performance was validated by experimental and structural analysis. The steel debris barrier has a high construction cost and causes environmental damage with corrosion. The construction of a concrete eco-pillar debris barrier has been increased recently. On the other hand, there are no design standards regarding debris barriers in Korea, and debris barriers are being designed by the experience and sense of engineers. Therefore, in this study, a method to determine the design external forces was proposed and the design was performed by applying a hollow cross-section to the debris barrier. In addition, three types of connection methods of a concrete cantilever column with the maximum bending moment acts were proposed, and validation of the performance of each type was performed with a real-scale experiment. The experimental results showed that the type with loop reinforcement had the highest rigidity and the type with anchorage performance exceeded the maximum bending moment according to the ultimate load. In the manufacturing procedure of mock-up debris barriers, the type with an anchorage-bar was found to have superior construct ability.

Case Study on the Hazard Susceptibility Prediction of Debris Flows using Surface Water Concentration Analysis and the Distinct Element Method (수계 집중도 분석 및 개별요소법을 이용한 토석류 위험도 예측 사례 연구)

  • Lee, Jong-Hyun;Kim, Seung-Hyun;Ryu, Sang-Hoon;Koo, Ho-Bon;Kim, Sung-Wook
    • The Journal of Engineering Geology
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    • v.22 no.3
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    • pp.283-291
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    • 2012
  • Various studies regarding the prediction of landslides are underway internationally. Research into disaster prevention with regard to debris flows is a particular focus of research because this type of landslide can cause enormous damage over a short period. The objective of this study is to determine the hazard susceptibility of debris flow via predictions of surface water concentrations based on the concept that a debris flow is similar to a surface water flow, as it is influenced by mountain topography. This study considered urban areas affected by large debris flows or landslides. Digital mapping (including the slope and upslope contributing areas) and the wetness index were used to determine the relevant topographic factors and the hydrology of the area. We determined the hazard susceptibility of debris flow by predicting the surface water concentration based on the topography of the surrounding mountainous terrain. Results obtained using the distinct element method were used to derive a correlation equation between the weight and the impact force of the debris flow. We consider that in using a correlation equation, this method could assist in the effective installation of debris-flow-prevention structures.

Debris Flow Analysis of Landslide Area in Inje Using GIS (GIS를 이용한 인제 산사태발생지역의 토석류 분석)

  • Kim, Gi-Hong;Yune, Chan-Young;Lee, Hwan-Gil;Hwang, Jae-Seon
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.29 no.1
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    • pp.47-53
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    • 2011
  • From 12 to 16 July 2006, 4 days' torrential rainfall in Deoksan-ri, Inje-up, Inje-gun, Gangwon-do caused massive landslide and debris flow. Huge losses of both life and property, including two people buried to death in submerged houses, resulted from this disaster. As the affected region is mostly mountainous, it was difficult to approach the region and to estimate the exact extent of damage. But using aerial photographs, we can define the region and assess the damage quickly and accurately. In this study the debris flow region in inje, Gangwon-do was analyzed using aerial photographs. This region was divided into three sections - beginning section, flow section and sedimentation section. Informations for each section were extracted by digitizing the shot images with visual reading. Topographic, forest physiognomic and soil characteristics and debris flow occurrences of this region were analyzed by overlaying topographic map, forest type map and soil map using GIS. Comprehensive analysis shows that landslide begins at slope of about $36^{\circ}$, flows down at $26^{\circ}$ slope, and at $21^{\circ}$ slope it stops flowing and deposits. Among forest physiognomic factors, species of trees showd significant relationship with debris flow. And among soil factors, effective soil depth, soil erosion class, and parent materials showed meaningful relationship with debris flow.

Prediction of a Debris Flow Flooding Caused by Probable Maximum Precipitation (가능 최대강수량에 의한 토석류 범람 예측)

  • Kim, Yeon-Joong;Yoon, Jung-Sung;Kohji, Tanaka;Hur, Dong-Soo
    • Journal of Korea Water Resources Association
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    • v.48 no.2
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    • pp.115-126
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    • 2015
  • In recent years, debris flow disaster has occurred in multiple locations between high and low mountainous areas simultaneously with a flooding disaster in urban areas caused by heavy and torrential rainfall due to the changing global climate and environment. As a result, these disasters frequently lead to large-scale destruction of infrastructures or individual properties and cause psychological harm or human death. In order to mitigate these disasters more effectively, it is necessary to investigate what causes the damage with an integrated model of both disasters at once. The objectives of this study are to analyze the mechanism of debris flow for real basin, to determine the PMP and run-off discharge due to the DAD analysis, and to estimate the influence range of debris flow for fan area according to the scenario. To analyse the characteristics of debris flow at the real basin, the parameters such as the deposition pattern, deposit thickness, approaching velocity, occurrence of sediment volume and travel length are estimated from DAD analysis. As a results, the peak time precipitation is estimated by 135 mm/hr as torrential rainfall and maximum total amount of rainfall is estimated by 544 mm as typhoon related rainfall.