• Title/Summary/Keyword: Stereonet projection

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Case Study of Slope Investigation on the Cretaceous Sedimentary Rocks Using the Geological Cross-Sections

  • Ihm, Myeong-Hyeok;Kim, Woo-Seok;Kwon, Oil
    • The Journal of Engineering Geology
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    • v.31 no.4
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    • pp.463-478
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    • 2021
  • The subjects of the study are the sedimentary rock slope of the Mesozoic Gyeongsang Supergroup, which has a high risk of failure. The orientation of the slope-face represents a variety of changing characteristics. The rocks of the slope shall be sandstone, siltstone and dacite, and discontinuities shall develop beddings, shear joints, extension joints, and dacite dyke boundary planes. The type and scale of failure varies depending on the type of rock and the strike/dip of the discontinuities, but the toppling failure prevails. Based on the face-mapping data, SMR, physical and mechanical testing of rocks, analysis and review of the stereonet projections and the critical equilibrium analysis, all four representative sections required a countermeasure method because the acceptable safety factor during dry and rainy seasons were far below Fs = 1.5 and Fs = 1.2. After applying the countermeasure method, both the dry and wet conditions of the slope exceeded the allowable safety factor. In particular, the face-mapping data of the slope-face, the geological cross-sections of several representative sections perpendicular to the slope-face, and the critical equilibrium analysis and the presentation of countermeasure methods that have been reviewed based on them are expected to be reasonable tools for the slope stability. In addition, it will be possible to use it as basic data for performance evaluation for slope maintenance.

Computational Treatment for Plotting of the Planar and the Linear Structures in Fault Zone (단층대내(斷層帶內)의 면(面) 및 선구조(線構造)의 도식화(圖式化)를 위한 전산처리(電算處理))

  • Sunwoo, Choon;Lee, Byung-Joo
    • Economic and Environmental Geology
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    • v.23 no.3
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    • pp.359-366
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    • 1990
  • Field sampling requires statistical description to draw inferences from data. Field data, or linear structures, are commonly analyzed by the graphical presentations, such as streonets and rose diagrams. For this purpose the DROPOL program is developed to analyze the data more efficiently with personal computer. DROPOL program written in FORTRAN 77 plots the structural data in points, poles or great circle on equalarea (Schmidt net) or equal-angle (Wulff net) projection surface. It is also capable to project the data from upper or lower hemisphere of stereonet and to draw pole contour diagrams from the plotted data. The rose diagram, representing the frequency of the strike and dip angle, can also be drawn in general or smooth type using $5^{\circ}$ or $10^{\circ}$ degrees interval.

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Stability Assesment of the Slope at the Disposal Site of Waste Rock in Limestone Mine (석회석 광산에서 폐석 적치장 사면의 안정성 평가)

  • Lee, Sang-Eun;Jang, Yoon-Ho
    • Tunnel and Underground Space
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    • v.20 no.6
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    • pp.475-490
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    • 2010
  • The analysis of slope stability was performed from seven sites among total eleven sites of waste rock which are divided into two objects (mullock-pile and rock mass) according to the location of dumping-dropping point in L limestone Mine. The analysis of circular failure using Bishop's simplified method and the finite element method for mullock-pile slopes were adopted. For rock mass slopes, identification of failure modes on stereonet projection was determined, thereby limit equilibrium analysis was applied to obtain the safety factor of slopes and the finite element method was used to understand overall behavior of slope. Phi-c reduction method was used to calculate the safety factor of slopes through the finite element method. In mullock-pile slope of zone D and rock slopes of zone F and G, the assurance of slope stability was difficult, and the plans to assure the stability of slopes were proposed on the basis of the analysis of slopes at disposal sites of waste rock. Therefore, the method of piling with waste rock by dozer pushing after dumping for mullock-pile slope of zone D is required, and the method of piling after moving to the place which has no fault zone for rock slope of zone F and G is recommended.

A Study on the Failure Cause of Large Scale Rock Slope in Limestone Quarries (석회석 광산에서 발생한 대규모 암반사면의 붕괴원인 분석에 관한 연구)

  • Lee, Sang-Eun;Kim, Hak-Sung;Jang, Yoon-Ho
    • Tunnel and Underground Space
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    • v.24 no.4
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    • pp.255-274
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    • 2014
  • The target of this study is large scale rock slope collapsed by around 7 pm on August, 2012, which is located at ${\bigcirc}{\bigcirc}$ limestone quarries of Gangneung city, Gangwondo. The slope prior to the collapse is formed as the height of about 200 m and the average inclination of $45^{\circ}$. The estimated amount of the collapse is about $1,500,000m^3$ with respect to the slope after the collapse. Geotechnical and field investigations such as boring, geophysical prospecting, surface geological survey, geological lineaments, borehole imaging, metric 3D imaging, experimental and field test, mining work by year, and daily rainfall were performed to find the cause of rock slope failure. Various analyzes using slope mass rating, stereonet projection, limit equilibrium method, continuum and non-continuum model were conducted to check of the stability of the slope. It is expected that the cause of slope failure from the results of various analysis and survey is due to the combined factors such as topography, rainfall, rock type and quality, discontinuities, geo-structural characteristics as the limestone cavity and fault zones, but the failure of slope in case of the analysis without the limestone cavity is not occurred. Safe factor of 0.66 was obtained from continuum analysis of the slope considering the limestone cavity, so the ultimate causes of slope failure is considered to be due to the influence of limestone cavity developed along fault zone.