• Title/Summary/Keyword: Collapsed rock slopes

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Estimation of Internal Friction Angle by the Back Analysis on Collapsed Rock Slope (붕괴된 암반사면에서 역해석에 의한 내부마찰각의 추정)

  • 이달원;김갑중
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.45 no.6
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    • pp.172-182
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    • 2003
  • In this study, the back analysis was performed by means of stereo-net, plane failure and block failure method to collapsed fields among the rock slopes designed by standardized criterion, and the internal frictions from the back analysis were compared with those used to reinforcement design. It was concluded that in the result of the analysis by means of stereo net, plain failure and block failure methods, the internal frictions used to re-design of collapsed slope underestimated 10$^{\circ}$, 5$^{\circ}$ and 10$^{\circ}$ in average. At present, the internal friction on the design is used the experience value according to the state of weathering, but internal friction angle by the back analysis on collapsed slope with various methods were more reliable values than those from the present method. And it was concluded that re-design was made extravagantly because the internal friction used to re-design for reinforcement of the collapsed slope was less than back analysis.

A Study on the Failure Characteristics for the Rock Slopes (Centering Around Jungang Highway) (암반사면의 붕괴특성에 관한 연구(중앙고속도로를 중심으로))

  • Kim, Jong-Ryeol;Lee, Jin-Su;Hwang, Pung-Ju;Lee, Yong-Hee
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.03a
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    • pp.765-776
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    • 2005
  • As a result of industrial advancement and land development, a number of highway slopes have been gradually formed and numerous problems related to their stability have been frequently caused. Generally, major factors for rock slope stability are lithology, slope inclination, slope height, degree of weathering, precipitation, condition of groundwater and so onl. Many complex factors are mostly involved in the collapse of rock slopes. In this study, a database for 94 collapsed Jungang highway slopes were set up using GIS program through literature search, site investigation, geological map and Korea tectonic province map. The analyses for the collapsed factor including sort of rock(by origin), tectonic province, highway direction, slope gradient and direction, degree of weathering, slope height were carried.

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Soft Sedimentary Rock Slopes Design of Diversion Tunnel

  • Jee, Warren Wangryul
    • Proceedings of the Korean Society for Rock Mechanics Conference
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    • 2007.10a
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    • pp.63-79
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    • 2007
  • Several remedial works were attempted to stabilize the collapsed area of the inlet slopes of diversion tunnel, but prevention of any further movement was being only carried out at beginning stage by filling the area with aggregates and rock debris, after several cracks had been initiated and developed around the area. The extra specialty developed folding zone is consisted with highly weathered Greywacke and Black shale. The suggested solution is to improve the properties of the rock mass of failed area by choosing the optimum level of reinforcement through the increment of slope rock support design so as to control the movement of slopes during the re-excavation. The Bakun hydroelectric project includes the construction of a hydroelectric power plant with an installed capacity of 2,520MW and a power transmission system connecting to the existing transmission networks in Sarawak and Western Malaysia. The power station will consist of a 210m height Concrete Faced Rockfill Dam. During the construction of the dam and the power facilities the Balui River has to be diverted of the tunnels is 12m and the tunnel width is 16m at the portal area. This paper describes the stability analysis and design methods for the open cut rock slopes in the inlet area of the diversion tunnels. The geotechnical parameters employed in stability calculations were given as a function of four defined Rock Mass Type (RMT) which were based on RMR system from Bieniawski. The stability calculations procedure of the rock slopes are divided into two stages. In the first stage, it is calculated for the stability of each "global" slope without any rock support and shotcrete system. In the second stage, it is calculated for each "local" slope stability with berms and supported with rock bolts and shotcrete. The monitoring instrumentation was performed continuously and some of the design modification was carried out in order to increase the safety of failed area based on the unforeseen geological risks during the open cut excavation.

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A Case Study of the Rock-fall Signal Lamp System for Preventing the Damage at the Cut-Slopes (사면붕괴 피해 예방을 위한 낙석신호등 설치 사례 연구)

  • Kim, Seung-Hyun;Koo, Ho-Bon;Rhee, Jong-Hyun;Baek, Yong
    • The Journal of Engineering Geology
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    • v.17 no.2 s.52
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    • pp.253-261
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    • 2007
  • The failure of the road cut-slope due to heavy rains brings about lots of injuries and damage on national properties. KICT has developed CSMS system by means of prevention to manage the dangerous cut slopes. In spite of the continuous management the frequency of cut-slopes failure is increasing the past due to changes of earth-environment. KICT has installed the "Real-Time Monitoring System" on dangerous slopes. The operation of Real-Time Monitoring System is used as a positive system to reduce injuries and damages. However, Although the slope manager is aware of the signs collapsed in advance, it has temporal and spatial limits until the slope manager performs the works which are preventing the accidents. When real time monitoring system finds out an indication of slope collapse, the Rock-fall Signal Lamp System makes road-users indicated the risk of cut slopes. It is a kind of prevention system that it will minimize the damages of the properties as suspension of traffic automatically or passively.

Mineral Composition Properties of Collapsed Cut Slope (붕괴절토사면의 광물조성 특성)

  • Kim, Jin-Hwan;Koo, Ho-Bon;Park, Mi-Sun;Baek, Young-Sik
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.03a
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    • pp.731-734
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    • 2005
  • Cut slopes are collapsed in Korea every year. Cut slope collapses cause a loss of lives and assets. Many researchers make clear collapse factor of cut lope. Fresh rock weathered through reaction undergroundwater and groundwater. During weathering process, weathered minerals are created. Weathered minerals are analysed by X-ray diffraction meter. X-ray diffraction meter make possible quantity assessment of degree of weathering and indicator of potential collapse possibilities. This paper discuss possibilities of cut slope dangerous with analysis of weathered minerals of cut slope.

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Displacements Behavior of Rock Slope by Shaking Table Test (진동대 실험을 통한 암반비탈면의 변위 거동 특성)

  • Yoon, Won-Sub;Kang, Jong-Chul;Park, Yeon-Jun
    • Journal of the Korean Society of Industry Convergence
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    • v.23 no.2_2
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    • pp.245-254
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    • 2020
  • This study investigated the so far little-researched characteristics of the behaviors of rock slopes at the time of an earthquake. For the selection of the rock block, a proper model was formed by applying the similarity in consideration of the roughness and strength of the rock slope(10m) on the site, and shaking table tests were carried out according to seismic excitement acceleration, and seismic waves. In the case of the inclination angle of the joint plane of 20°, the long period wave at 0.3g or more at the time of the seismic excitement surpassed the length of 100mm, the permissible displacement (0.01H, H:slope height), which brought about the collapse of the rock; the short period wave surpassed the permissible displacement at 0.1g, which caused the collapse of the slope. The rock slope was close to a rigid block and a structure more vulnerable to the long period wave than to the short period wave. It collapsed in the short period wave even at the seismic amplitude smaller than the maximum design acceleration in Korea.

Study on Suggestion a Standard Installation for Damage Reduction alarm System using Cut-Slope Data (국내 도로절개면 현황 및 붕괴 분석을 통한 경보시스템 설치 기준에 관한 기초적 연구)

  • Bae, Gyu-Jin;Koo, Ho-Bon;Baek, Yong
    • The Journal of Engineering Geology
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    • v.12 no.1
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    • pp.53-61
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    • 2002
  • Cut-slope due to the road construction is one of the most significant problems in the domestic case, that is, 70% of the land is covered by mountain. Moreover, typhoons or heavy rains concentrated in summer season causes the failure of cut-slope. Rock-fall and soil slope failure take 40.8% and 29.5% out of the entire domestic cut-slope failure, respectively. Rock-fall is quickly occurred by the free fall or rolling of rock fragments generally in the upper slope. Soil slope failure produces a clastics-flow and increases casualty especially when caused by heave rainfall because the velocity of the movement is verb high. Considering the car speed and rock-fall velocity, it will take a life in a moment. This study analyzes a set of field data of most recently collapsed domestic road cut-slopes to characterize these cut-slopes and the nature of rock-falls and clastics flows at each site. Based on the results, design criteria for a road alarm system are proposed, considering the relationship between the time required for clastics-flow and the velocity and braking distance of a cat at the incidence. The road alarm system proposed herein would operate instantly after a rock-fall and it will minimize damages, by warning drivels approaching to the collapse or collapsing location in advance.

Analysis of Priority Investments for Preventing Roadside Slope Failures (도로비탈면 투자우선순위 결정에 관한 연구)

  • Kim, Seung-Hyun;Kim, Hong-Gyun;Oak, Young-Suk;Lee, Jong-Hyun;Koo, Ho-Bon
    • The Journal of Engineering Geology
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    • v.23 no.3
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    • pp.257-269
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    • 2013
  • Prevention plans for landslide and slope disasters should be appropriate for a country's budget when considering a systematic investment plan. The systematic management of slopes adjacent to national highways should incorporate reasonable investment risk and the expected degree of damage should be calculated by considering the investment priorities. In terms of priority of investment, the major factors used to determine the degree of hazard are gradient, soil characteristics, RMR (Rock Mass Rating), stability interpretation, type of discontinuities, and history of collapse, among others. The likely consequences of slope failure can be determined by considering traffic volume, the number of lanes, and average vehicle risk. We performed such calculations regarding the priority of investment and performed a regression analysis for 392 slopes located in Yeongseo region, Gangwon province. The calculation results show that collapsed slopes have a higher priority for investment, as do slopes with a high proportion of dangerous sections and locations in valleys.

Geotechnical characteristics of the collapsed $\bigcirc\bigcirc$tunnel slope in Yeosu-Suncheon area (여수-순천 도로확장공사 구간 $\bigcirc\bigcirc$터널 붕괴사면 지반특성)

  • Kim, Seung-Hyun;Koo, Ho-Bon;Lee, Jeong-Yup;Rhee, Jong-Hyun;Kim, Seung-Hee
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.03a
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    • pp.848-857
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    • 2008
  • In September 2007, the collapses of slopes and landslides are happened at Jeonlanamdo due to heavy rains accompanied with Typoon "Nari". The study area is the tunnel portal slope in new road construction site. This slope consists of pyroclastic rocks and has lots of faults. Particularly, the residual soils of the slope is deteriorated with yellowish mudstone layer as a results of chemical and physical weathering. This has a variety of swelling clay minerals and might be moved easily down at the gentle terrain. The inner factor of $\bigcirc\bigcirc$tunnel portal slope's collapse is the geological weak zone, the convergent topography, the inferiority of drainage and the heavy rain act on the failure as direct trigger.

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A Study on Jointed Rock Mass Properties and Analysis Model of Numerical Simulation on Collapsed Slope (붕괴절토사면의 수치해석시 암반물성치 및 해석모델에 대한 고찰)

  • Koo, Ho-Bon;Kim, Seung-Hee;Kim, Seung-Hyun;Lee, Jung-Yeup
    • Journal of the Korean Geotechnical Society
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    • v.24 no.5
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    • pp.65-78
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    • 2008
  • In case of cut-slopes or shallow-depth tunnels, sliding along with discontinuities or rotation could play a critical role in judging stability. Although numerical analysis is widely used to check the stability of these cut-slopes and shallow-depth tunnels in early design process, common analysis programs are based on continuum model. Performing continuum model analysis regarding discontinuities is possible by reducing overall strength of jointed rock mass. It is also possible by applying ubiquitous joint model to Mohr-Coulomb failure criteria. In numerical analysis of cut-slope, main geotechnical properties such as cohesion, friction angle and elastic modulus can be evaluated by empirical equations. This study tried to compare two main systems, RMR and GSI system by applying them to in-situ hazardous cut-slopes. In addition, this study applied ubiquitous joint model to simulation model with inputs derived by RMR and GSI system to compare with displacements obtained by in-situ monitoring. To sum up, numerical analysis mixed with GSI inputs and ubiquitous joint model proved to provide most reliable results which were similar to actual displacements and their patterns.