• 제목/요약/키워드: Mountain slope

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Kinematic Analysis of Plane Failure for Rock Slope Using GIS and Probabilistic Analysis Method (GIS와 확률론적 해석 기법을 기반으로 한 평면파괴의 운동학적 안정성 해석)

  • Lee, Seok Hwan;Park, Hyuck Jin
    • Economic and Environmental Geology
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    • v.47 no.2
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    • pp.121-131
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    • 2014
  • The stability of rock slope is mainly controlled by the orientation and shear strength of discontinuties in rock mass. Therefore, in kinematic analysis, the orientation of the combination of discontinuities and slope face is examined to determine if certain modes of failure can be occurred. In previous kinematic analysis, a representative orientation of the slope face and mean orientation of discontinuity set were used as input parameters. However, since the orientations of slope face varies according to locations of measurement, the representative slope face orientation could cause misunderstanding for kinematic instability. In addition, since the orientations of each discontinuity are scattered in the same discontinuity set, there is the possibility that uncertainties are involved in the procedure of kinematic analysis. Therefore, in this study, the detailed digital topographic map was used to obtain the orientation of slope face. In addition, the probabilistic analysis approach was utilized to deal properly with the uncertainties in discontinuity orientation. The proposed approach was applied to steep slopes in mountain road located in Baehuryeong, Chunncheon city, Gangwon-Do. The analysis results obtained from the deterministic and probabilistic analysis were compared to check the feasibility of proposed the analysis.

Modification of Sea Water Temperature by Wind Driven Current in the Mountainous Coastal Sea

  • Choi, Hyo;Kim, Jin-Yun
    • Proceedings of the Korean Environmental Sciences Society Conference
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    • 2003.11a
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    • pp.177-184
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    • 2003
  • Numerical simulation on marine wind and sea surface elevation was carried out using both three-dimensional hydrostatic and non-hydrostatic models and a simple oceanic model from 0900 LST, August 13 to 0900 LST, August 15, 1995. As daytime easterly meso-scale sea-breeze from the eastern sea penetrates Kangnung city in the center part as basin and goes up along the slope of Mt. Taegullyang in the west, it confronts synoptic-scale westerly wind blowing over the top of the mountain at the mid of the eastern slope and then the resultant wind produces an upper level westerly return flow toward the East Sea. In a narrow band of weak surface wind within 10km of the coastal sea, wind stress is generally small, less than l×10E-2 Pa and it reaches 2 × 10E-2 Pa to the 35 km. Positive wind stress curl of 15 × 10E-5Pa m1 still exists in the same band and corresponds to the ascent of 70 em from the sea level. This is due to the generation of northerly wind driven current with a speed of 11 m S1 along the coast under the influence of south-easterly wind and makes an intrusion of warm waters from the southern sea into the northern coast, such as the East Korea Warm Current. On the other hand, even if nighttime downslope windstorm of 14m/s associated with both mountain wind and land-breeze produces the development of internal gravity waves with a hydraulic jump motion of air near the coastal inland surface, the surface wind in the coastal sea is relatively moderate south-westerly wind, resulting in moderate wind stress. Negative wind stress curl in the coast causes the subsidence of the sea surface of 15 em along the coast and south-westerly coastal surface wind drives alongshore south-easterly wind driven current, opposite to the daytime one. Then, it causes the intrusion of cold waters like the North Korea Cold Current in the northern coastal sea into the narrow band of the southern coastal sea. However, the band of positive wind stress curl at the distance of 30km away from the coast toward further offshore area can also cause the uprising of sea waters and the intrusion of warm waters from the southern sea toward the northern sea (northerly wind driven current), resulting in a counter-clockwise wind driven current. These clockwise and counter-clockwise currents much induce the formation of low clouds containing fog and drizzle in the coastal region.

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Soil Properties of Granitic Weathered Soils in the Landslide-prone Areas in Seoul (서울지역 화강암 풍화토 토층지반의 토질특성)

  • Kim, Kyeong-Su
    • The Journal of Engineering Geology
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    • v.29 no.1
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    • pp.23-35
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    • 2019
  • Landslides occur due to heavy rainfall in the summer season. Some of water may infiltrate into the ground; it causes a high saturation condition capable of causing a landslide. Soil properties are crucial in estimating slope stability and debris flow occurrence. The main study areas are Gwanaksan, Suraksan and Bukhansan (Mountain) in Seoul. A total of 44 soil samples were taken from the study area; and a series of geotechnical tests were performed. Physical and mechanical properties were obtained and compared based on region. As a result, among well-graded soils, they are classified as a clayey sand. Coarse-grained and fine-grained contents are approximately 95% and 5%, respectively, with very low amount of clay content. Density, liquid limit and dry unit weight are ranged in 2.622.67g/cm3, 27.93~38.15% and 1.0921.814g/cm3. Cohesion and internal friction angle are 4 kPa and 35 regardless of mountain area. Coefficient of permeability is varied between 3.07×1034.61×102cm/sec; it means that it results in great seepage. Permeability is inversely proportional to the uniformity coefficient and is proportional to the effective particle size. In the formal case, there was a difference by mountain area, while in the latter, the tendency was almost similar.

Material Analysis and Provenance Interpretation for Rock Properties of the Gwangjueupseong (Gwangju Town Wall), Korea (광주읍성 축성암석의 재질분석과 산지해석)

  • Lee, Myeong-Seong;Chun, Yu-Gun;Seo, Jeong-Seog;Lee, Chan-Hee
    • Journal of Conservation Science
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    • v.25 no.1
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    • pp.61-76
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    • 2009
  • Gwangjueupseong (Gwangju Town Wall) has been found in the site of the Asian Culture Complex (former Provincial Government of Jeonnam) by archaeological field survey. The length of the remaining wall is 85.1m, and the Town Wall consists of ten kinds of rock type. The major rock types are dacite (41.1%) and andesite (35.7%). Dacite composes main rock blocks of the wall, and andesite is used to fill the cavity between main rock blocks. These rocks look very similar to basement rocks of the Mudeung Mountain on the basis of occurrence features, magnetic susceptibility, petrological, mineralogical and geochemical properties. Also, quarrying traces were found on the southwestern slope of the mountain along the Jeungsimsa Temple valley. Thus, it is probable that the rock materials of the Gwangju Town Wall were supplied from the Mudeung Mountain and that they were transported along the Gwangju river.

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Landslide Risk Analysis due to Development of Mountain Area (산지지역 개발에 의한 산사태 위험 분석)

  • Namgyun Kim;Yunseong Park
    • Journal of Korean Society of Disaster and Security
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    • v.16 no.4
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    • pp.67-74
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    • 2023
  • In this study, the risk of landslides was analyzed for planned development sites in mountainous areas. Field survey was conducted on the research area with the slope and valley site. The criteria for evaluating the risk of landslides in the field survey were based on the risk assessment table of the Korea Forest Service Notice No. 2023-10. The research area has 13 slopes and 11 valleys. As a result of evaluating the risk area, two slopes and two valley were found to be dangerous sites in each. Numerical simulation was performed on the investigated risk areas to predict the spread of damage. The debris flow was simulated to have an affect on roads and buildings located in the lower part of the basin, and it was determined that a disaster prevention facility was nacessary to minimize damage. This information can be used to determine the impact of disasters before carrying out mountain development.

Development and Application of the Slope Management Program in Urban Area (대도시 사면관리프로그램 개발 및 적용)

  • Kim, Kyeong-Su;Chae, Byung-Gon;Cho, Yong-Chan;Lee, Choon-Oh;Song, Young-Suk
    • The Journal of Engineering Geology
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    • v.17 no.1 s.50
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    • pp.15-25
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    • 2007
  • In general, the life and asset casualties that occur due to landslide or slope failure in urban areas are larger than that in rural areas. In order to reduce the casualties, a slope management program is necessary to categorize slopes based on properties and to manage them systematically. The slope management system is the establishment of the data base for the geological and geotechnical factor according to slope stability, and the utilization of the data base to manage slopes. The suitable system must develop to slopes in urban area through the survey, analysis and evaluation process. Based on the above necessity, the slope management program which is applicable to slope management in an urban area has been developed at Hwangryung Mt. in Busan as a target area. The developed slope management program has various functions such as slope ID number of each slope or sub-region of a mountain, making a slope data sheet, analysis and grouping of slope stability, and establishment of a data base. The slope management program is constructed by use of GIS, and the survey, test and analysis data according to all slopes can be input and edited into the program. The program can also be utilized practically by end users due to the convenient input, edition printing, management and operation of slope data. Therefore, the slope management system has been established on the application of the developed program in Busan which is located in slope area. As the system is widely applied to other cities, the slope in urban area can be managed systematically and the slope hazards can be minimized.

Case study of landslide types in Korea (우리나라 산사태의 형태분류에 따른 사례)

  • 김원영;김경수;채병곤;조용찬
    • The Journal of Engineering Geology
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    • v.10 no.2
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    • pp.18-35
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    • 2000
  • The most dominant type of landslide in Korea is debris flows which mostly take place along mountain slopes during the rainy season, July to August. The landslides have been reported to begin activation when rainfall is more than 200mm within 2days. The debris flows are usually followed by translational slips which occur upper part of mountain slopes and they transit to debris flow as getting down to the valleys. Lithology, location, slope inclination, grain size distribution of soil, permeability, dry density and porosity have been proved as triggering factor causing translational slides. The triggering data taken from mapping are statistically analysed to get landslide potential quantitatively. Rock mass creeps mostly occur on well bedded sedimentary rocks in Kyeongsang Basin. Although the displacement of rock mass creep is relatively small about 1m, the creep can cause severe hazards due to relatively large volume of the involved rock mass. Examples are rock mass creep occurred in the mouth of Hwangryongsan Tunnel, in Chilgok and in Sachon in 1999. Although the direct factor of the creeps are due to slope cutting at the foot area, more attention is required A rotational slide occurring within thick soil formation or weathered rock is also closely related to bottom part of slope cutting. It is propagated circular or semi-circular type. Especially in korea, the rotational slide may be frequently occurred in Tertiary tuff area. Because they are mainly composed of volcanic ash and pyroclastic materials, well developed joints and high degree of swelling and absorption can easily cause the slide. The landslide among the Pohang-Guryongpo national road is belong to this type of slide.

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Characteristics of Steep Shingi Gully with Channelized Debris Flows (계곡형 토석류가 발생한 급경사 신기 계곡의 특성)

  • Park, Sang Doeg;Kim, Yong Hyun;Ham, Gwang Hyun;Son, Sang Jin;Na, Raksmey;Kim, Nam Jin
    • Journal of The Geomorphological Association of Korea
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    • v.28 no.3
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    • pp.13-26
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    • 2021
  • In mountain gully, channelized debris flow is an important phenomenon in the process of topographical change. Social infrastructure as roads may be damaged by channelized debris flows, but there has been little information about their occurrence and movement to prepare for the risk of the debris flow. Most of the channelized debris flows occur during heavy rains in mountainous valleys that are difficult to access, so there are not many field data. In this study, the topographical characteristics of the catchment, the rainfall and runoff related to the debris flow, the sedimentary pattern and the cross-sectional change of the channel bed, and the underflow velocity of the gravel bed have been investigated and analyzed in the Singi gully where the channelized debris flows occurred. In the catchment, there was almost no sediment runoff because the vegetation combine with the debris landforms and covered the surface. Therefore, the obvious cause of the channelized debris flows is the collapse of the slope and bed of the gully. Even if the gravel, cobbles, and boulders of the channel bed were lost by debris flow, the thalweg change due to debris flow may not be significant because they are supplied from the gully side slope normally. After the gabion structures were installed, the debris flow increased the thalweg change, bed erosion and side slope of the gully. Various sedimentary structures in the gully were classified according to the factors supporting the sedimentation. The hypsometric curve of the gully reflects the debris landforms and vegetation characteristics of the watershed and the sediment runoff due to debris flow, etc. The relationship between the flow velocity and the hydraulic gradient was non-linear under the condition that the porous medium with gully bed gravels is saturated with water. These results may be used as basic data for channelized debris flow research.

Analysis of Ancient Document and Establishment of Petrological Database for Presumption of Stone Source Area of the Seoul City Wall, Korea (한양도성 석재공급지 추정을 위한 고문헌 분석 및 암석학적 데이터베이스 구축)

  • Jo, Young Hoon;Lee, Chan Hee
    • The Journal of the Petrological Society of Korea
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    • v.24 no.3
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    • pp.193-207
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    • 2015
  • This study analyzed ancient documents and established petrological database through extensive field investigation of provenance sites to presume stone source areas of the Seoul City Wall. By summarizing the ancient documents, the rampart stone was mostly supplied from a stony mountain adjacent to the City Wall in the early Joseon period, whereas the stone was provided from fixed quarry outside the City Wall in the late Joseon period. As a result of the petrological investigation based on quarries recorded in the ancient documents, pinkish granite and leucogranite were distributed as a whole, and the granitoid rocks are similar in mineralogical compositions and geochemical behavior characteristics. However, the pinkish granite with magnetic-series show that the magnetic susceptibility increased from the north slope of Namsan Mountain to Bulamsan Mountain. The leucogranite with ilmenite-series mainly occurred along the boundary between granite and gneiss from Yongmasan Mountain to Inwangsan Mountain. Consequently, the important petrological indicators for presumption of stone source areas are the rock color and the magnetic susceptibility. In addition to the petrological features, the reliability for provenance interpretation should improve considering stone quantities in the quarries, transportation distance and technical skills.

Design and Implementation of the Slope-Crack Prediction System by Using Wireless Sensor Networks (무선 센서 네트워크를 이용한 상시 사면 균열 예측시스템의 설계 및 구현)

  • Lim, Hwa-Jung;Tscha, Yeong-Hwan
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.13 no.1
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    • pp.186-192
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    • 2009
  • With the proliferation of ubiquitous computing we have witnessed the wide application of many wireless sensor networks into various areas because of easy installations and low-cost merits. The commercially available equipments for monitoring and predicting cracks in the mountain regions are still burden for us in terms of the installation complexity and the cost. Alternatively we in this paper design and implement a pilot slop-crack monitoring and prediction system which is based on low-cost commercial sensor networks. The proposed system is easy to install on cliffs, slopes, rocks, and banks and may minimize the destruction of the original geographical forms. Expected is that its installation and maintenance costs may reduce to the half of those of existing systems.